Case No: B3/2001/0382, B3/2001/0123, B3/2001/0616,
B3/2000/2431, B3/2001/0939, B3/2001/1653 and
B3/2001/1669
IN THE SUPREME COURT OF JUDICATURE
COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM QUEEN’S BENCH DIVISION 
Curtis J
Royal Courts of Justice
Strand, London, WC2A 2LL

Date: 11th December 2001
B e f o r e :

LORD JUSTICE BROOKE
LORD JUSTICE LATHAM
and 
LORD JUSTICE KAY

- - - - - - - - - - - - - - 

Between										              

B3/2001/0382	JUDITH FAIRCHILD
(Suing as Administratrix and Widow of ARTHUR ERIC FAIRCHILD
Deceased)
- and -
GLENHAVEN FUNERAL SERVICES LTD
-and-
WADDINGTONS PLC
-and-
LEEDS CITY COUNCIL

And five other appeals whose names appear on the following page

	Claimant/Appellant

First Defendants

Second Defendants/
Respondents
Third Defendants
Respondents	

- - - - - - - - - - - - - - 
- - - - - - - - - - - - - -

Brian Langstaff QC & Andrew Hogarth (instructed by O H Parsons & Partners for the Appellant)
Stephen Stewart QC & Michael Rawlinson (instructed by Halliwell Landau for Waddingtons plc)
Michael Taylor (instructed by Leeds City Legal Services Department for the Leeds City Council)

Judgment
As Approved by the Court

Crown Copyright ©

- - - - - - - - - - - - - - - - -

B3/2001/0123
Judge Bush

B3/2001/0616
Judge Tetlow

B3/2000/2431
Eady J

B3/2001/0939
Judge Mackay

B3/2001/1653
& 1669
Mitting J

	ROBERT ALAN DYSON
- and –
JOHN WATSON FIELD
(suing as executors of LAWRENCE TWOHEY Deceased)
-	-and-
LEEDS CITY COUNCIL

ROBERT PENDLETON
- and -
STONE & WEBSTER ENGINEERING LTD
-and-
BG PLC
-and-
POLYCOL LTD
-and-
CO-OPERATIVE WHOLESALE SOCIETY LTD

BABCOCK INTERNATIONAL LTD
- and -
NATIONAL GRID COMPANY PLC

DOREEN FOX
(suing as Widow and Administratrix of THOMAS FOX Deceased)
- and -
SPOUSAL (MIDLAND) LTD

EDWIN MATTHEWS
- and -
ASSOCIATED PORTLAND CEMENT MANUFACTURERS (1978) LTD
-and-
BRITISH URALITE PLC

Claimants/Appellants

Defendant/Respondent

Claimant/Respondent

Defendants

First Appellants

Second Appellants

Third Appellants

Claimant/Appellant

Defendant/
Respondent

Claimant/Appellant

Defendant/
Respondent

Claimant/Respondent

Defendants/Appellants

B3/2001/0123
David Allan QC & Mark Grenyer (instructed by Lawfords for the Appellants)
Michael Taylor (instructed by Leeds City Legal Services Department for the Respondents)

B3/2001/0616
Michael Taylor (instructed by Praxis Partners for the Appellants)
David Allan QC (instructed by Thompsons for the Respondents)

B3/2000/2431
Edward Faulks QC & Simon Levene (instructed by Vizards Staples & Bannisters for the Appellant)
Richard Nussey (instructed by Greenwoods for the Respondent)

B3/2001/0939
David Allan QC (instructed by John Pickering & Partners for the Appellant)
Nigel Wilkinson QC & William Vandyck (instructed by AMP (UK) Services Legal Department for the Respondent)

B3/2001/1653 and B3/2001/1669
Robert Owen QC & Charles Feeny (instructed by Berrymans Lace Mawer for the Appellant)
David Allan QC (instructed by John Pickering & Partners for the Respondent)

SUMMARY
(This Summary does not form part of the judgment of the court)

	In these six appeals the Court of Appeal has decided three different issues which arise in cases where a claimant has suffered, or may suffer, asbestos-induced mesothelioma after being exposed to asbestos dust after working for more than one employer.

	In Fairchild, Fox and Matthews the court held that in these circumstances a claimant cannot recover damages.  The reason for this is that mesothelioma, unlike asbestosis or pneumoconiosis, is a single indivisible disease (see paras 21-28), and a claimant cannot establish on the balance of probabilities when it was that he inhaled the asbestos fibre, or fibres, which caused a mesothelial cell in his pleura to become malignant (see paras 102-108). The court observed that in these circumstances claimants may have a claim under the Pneumoconiosis (Workers’ Compensation) Act 1979, in which event the cost to the exchequer may run into tens of millions of pounds each year.  If they do not, it said that these cases have revealed a major injustice crying out to be righted either by statute or by an agreed insurance industry scheme (see para 107).

	In Babcock, Fairchild and Dyson the court held that no liability attaches to an occupier of premises whether at common law prior to 1957 or under the Occupiers’ Liability Act 1957 from the mere fact that the workmen in these cases were exposed to asbestos dust in premises of which they were the occupiers.  The language of section 2(2) of the 1957 Act, which referred to “care … to see that the visitor will be reasonably safe in using the premises for the purposes for which he is invited or permitted  by the occupier to be there” relates to the static condition of the premises.  Any liability in respect of a danger to which the workmen may be exposed as a consequence of activities performed on the premises falls to be determined by the common law (or by a different statute, such as section 63(1) of the Factories Act 1961).  In these three cases, where the occupiers engaged competent independent contractors to carry out work on their premises, and where the occupiers did not know of the danger to which the workmen were exposed (even though they ought to have known it, at any rate from 1958 onwards), they were not liable for negligence at common law simply in their capacity as occupiers (see paras 149-155).

	In Pendleton the court held that on the proper construction of section 51(1) of the County Courts Act 1984 it was open to a court in a case like this to make an order for provisional damages to cover the risk of the claimant contracting mesothelioma or lung carcinoma at some future date as a consequence of his exposure to asbestos dust even though he would not be able to recover damages today in respect of such diseases in the present state of medical science and the law (see para 166).
-	

Contents

Part No									Para No
    1.	Introduction								        1
    2.	The Facts:
	        (i)  Arthur Fairchild						        4
	       (ii)  Thomas Fox							        8
	      (iii)  Edwin Matthews						      10
	      (iv)  John Hussey							      14
	       (v)  Lawrence Twohey						      16
	      (vi)  Robert Pendleton						      18
3.	Mesothelioma and asbestosis:
	        (i)  Mesothelioma							      21
	       (ii) Asbestosis							      27
    4.	The causation caselaw:
	        (i)  Bonnington Castings, Nicholson and Gardiner		      29
	       (ii)  McGhee							      37
	      (iii)  Thompson, Bryce and Wilsher				      52
	      (iv)  Some Commonwealth cases 					      64
	       (v)  Holtby								      68
    5.	The judgments on causation in the courts below:
	        (i)  Fairchild							      72
	       (ii)  Fox								      75
	      (iii)  Matthews							      76
    6.	Causation: the arguments						      78
    7.	Conclusion: Causation							    102
    8.	Occupiers’ liability: the law
	        (i)  Three different issues of law					    109
	       (ii)  Section 63(1) of the Factories Act 1961			    111
	      (iii)  The common law liability of an occupier before 1957	    113
	      (iv)  The Occupiers’ Liability Act 1957 and common law
 liabilities since 1957						    122
    9.	Occupiers’ Liability:  The judgments. 
	        (i)  Babcock							    134
	       (ii)  Dyson							    138
	      (iii)  Fairchild							    143
  10.	Occupiers’ Liability:  Conclusions					    149
  11.	Pendleton: Provisional Damages					    156
  12	The result of these appeals						    167

JUDGMENT : APPROVED BY THE COURT FOR HANDING DOWN (SUBJECT TO EDITORIAL CORRECTIONS)

Lord Justice Brooke :  This is the judgment of the court.
1.	Introduction
1.	These six appeals were heard together.  They raise two important points.  The first is whether a claimant suffering from mesothelioma can recover compensation from anyone who negligently exposed him to significant amounts of asbestos dust if he did not remain in the same employment throughout the period of exposure. The second is whether, in the event that he cannot identify any relevant employer who is still viable and/or insured, he can recover compensation from the occupiers of the premises where he was exposed to asbestos dust in significant amounts.  One appeal, Pendleton v Stone & Webster Engineering Ltd, raises a particular issue about the appropriateness of an order for provisional damages in a mesothelioma case where there has been more than one period of negligent exposure to asbestos dust.
2.	We will refer to the different appeals by the names of the different claimants.  They fall into three categories.  Fairchild, Fox and Matthews fall into the first category, Fairchild, Babcock and Dyson into the second and Pendleton into the third.  The cases in the first category raise what we will call “the causation issue”. In the “occupiers’ liability” cases in the second category the judges ruled consistently in favour of the defendant occupiers.  In one of them, Babcock, the judge said that if he was wrong about this, he would have apportioned liability as to 100% against the negligent employers as opposed to the occupiers of the premises in which the dust arose.  Pendleton raises, as we have said, the provisional damages issue, on which the judge ruled in favour of the claimant. We will describe the facts of these six cases in paragraphs 4-20 below, and summarise the effect of the different judges’ rulings in paragraphs 72-77, 134-148 and 156-164 below.
3.	When opening the Fairchild appeal Mr Langstaff QC described the perceived merits of asbestos.  It is a mineral silicate which is very useful for insulation purposes.  It is fireproof, acid proof, and resistant to alkalis and moisture.  It is also very easy to shape and to apply.  Sadly, its dust possesses qualities that have proved to be very injurious to human health; and awareness of the damage it did was very slow to percolate among those who profited from its benefits.  The six histories we are about to set out have been replicated many, many times in asbestos litigation all over the world in the last 30 years.
2.	The Facts:  (i)  Arthur Fairchild
4.	Arthur Fairchild was born in 1935.  His first job was as a joiner for a firm called G H Dovener & Son.  He worked for that firm between 1950 and 1962, apart from two years’ National Service.  He was sometimes engaged in work which included making large industrial packing cases for ovens lined with asbestos.  He was then sent on outside maintenance jobs for the Leeds City Council, most notably, in about 1962, on a major renovation job at Meanwood Swimming Baths.  Between 1962 and 1964 he worked as a concrete floor maker for Bisons Floors.  He then got a job for the next four years with B Slack & Sons, a firm of general builders.  At one time he was engaged by this firm as a roof repairer, where he would from time to time handle and cut corrugated asbestos cement sheets.  He then worked for them for a time as a joiner at a former Ministry of Food building that had been acquired by Waddingtons at Patrick Green, Leeds, which was being gutted and converted into a factory.  The main job there lasted between six and eight months, and he later made periodic maintenance visits to the factory now on the site.  Between 1968 and 1970 he worked for two road-making companies  He then returned to work for Bisons Floors for the next 26 years.
5.	In 1995 he began to exhibit signs of mesothelioma.  The onset of symptoms was first noted in about May 1995, and he had to give up work in February 1996, when he knew he was dying.  He died in September 1996.  The judge said that it was difficult to imagine a more drawn out or painful way in which to die, but he bore it all with fortitude.  He was on massive doses of morphine as he reached his end.  By the end his right lung was obliterated by a massive tumour, which had also invaded his chest wall, diaphragm and pericardium.
6.	He had no exposure to asbestos when he was working for Bisons Floors and the two road-making companies.  His two other employers had long since ceased to trade, and their employers’ liability insurers could not be traced.  It was originally thought, incorrectly, that the first named defendants were the lineal successors to G H Dovener, but when it was realised that they were not, the proceedings against them were dismissed.  The action by Mr Fairchild’s widow then continued against the occupiers of the two buildings in which he was said to have had “meaningful” exposure to asbestos: Leeds City Council (in respect of Meanwood Baths) and Waddingtons (in respect of the works at their premises at Patrick Green).  
7.	He was exposed to substantial quantities of asbestos fibres on each site.  This exposure was created by workmen employed by other contractors.  In the later period of his exposure at Waddingtons that company admittedly owed him a duty pursuant to section 63 of the Factories Act 1961 in addition to whatever duties they may have owed him under the Occupiers’ Liability Act 1957 or at common law.  It was admitted that on each of these jobs Mr Fairchild was exposed to substantial quantities of lagging-derived asbestos containing debris and dust.  He was also exposed to asbestos dust, to a much lesser extent, during the course of other work he did for these two employers.  Both causation and the occupiers’ liability issues were live issues on this appeal.
(ii)  Thomas Fox
8.	Thomas Fox was born in 1933.  In 1953 he went to work for between 18 months and two years for the defendants, who were then called Joseph Nadins.  They employed him as a pipelagger.  After that he worked for many years as a docker under the national dock labour scheme for many different shipping lines at the Liverpool and Merseyside Docks.  He retired in 1989, slightly earlier than the normal retiring age.
9.	Mr Fox came into contact with asbestos dust both as a lagger and in his work at the docks, where he would unload asbestos cargoes from time to time.  He developed lung symptoms a short period before his death.  A diagnosis of malignant mesothelioma was made, and he died in April 1996.  The judge said that his death was as unhappy, unfortunate and painful as one could imagine.  He lost six stones in weight in the last three months of his life.  Causation is the only issue that arises for decision on this appeal.
(iii)  Edwin Matthews
10.	Edwin Matthews was 54 at the time of the trial in July 2001.  Between 1962 and 1984 he did a variety of jobs which brought him into contact with asbestos.  It was common ground that he suffered exposure to asbestos in significant quantities when working for three of his 15 employers during this period, the two defendant companies and a firm called Maidstone Sack and Metal, for whom he worked between May 1965 and May 1967.  That company is no longer viable, and is not a party to this action.
11.	So far as the two defendants are concerned, he worked for the second defendants British Uralite plc for five or six weeks in early 1973 at a factory in Higham, Kent, which was engaged in the manufacture of asbestos drainage pipes.  The judge accepted Mr Matthews’s evidence to the effect that this factory was notorious for its appalling working conditions.  There was asbestos dust on his work station, and all over the floor, and he raised dust as he worked.  At the end of the day he was white with asbestos dust.  It was in his hair and all over his clothes.
12.	He moved to a job with the first defendants, who were then called Blue Circle Industries Limited.  He worked for them at Strood between February 1973 and February 1981.  During the last four years of this employment he worked as a boilerman, where he came into contact with asbestos.  Their large boiler was lagged with asbestos, as was the pipework to the boiler, and this asbestos lagging was dry and dusty.  He spent between 45 minutes and an hour in the boiler house each day.
13.	He started suffering from anterior chest pain of a pleuritic nature in February 1999, and he received treatment from time to time during the course of that year.  In March 2000 he was diagnosed as suffering from mesothelioma of the pleura.  His disease progressed more slowly than the average, but his expectation of life has been severely shortened.  Both the defendants admitted that he was exposed to asbestos dust while in their employment and that they were in breach of statutory and common law duties in allowing him to be so exposed.  Causation is the only live issue on this appeal.
(iv)  John Hussey
14.	John Hussey died in August 1993 from mesothelioma.  His former employers Babcock International Ltd (“Babcock”) paid £80,000 damages to his widow.  The judge was concerned with Babcock’s claim for contribution from National Grid plc, as successors in title to the Central Electricity Generating Board (“CEGB”), who were the owners and occupiers of Barking and Battersea Power Stations in the early 1950s.  It was common ground that Mr Hussey’s condition derived from his exposure to asbestos dust and fibres at those two power stations, probably between September 1953 and December 1955.
15.	During that time Babcock, who were well known as specialist suppliers of boilers and associated pipework, were undertaking major construction and installation projects for the CEGB.  The boilers and pipework were lagged (to a greater or lesser extent, depending on the temperature) with material containing asbestos.  This would have been standard practice, and the judge said that it would also no doubt have been specified by the CEGB.  Several hundred tonnes of lagging material would be used in a typical power station at that time, and there was a great deal of asbestos dust or fibre in the atmosphere when the lagging work was carried out.  The occupiers’ liability issue and apportionment of liability are the issues that arise on Babcock’s appeal.
(v)  Lawrence Twohey
16.	Lawrence Twohey was born in August 1930.  He was employed by J W Atkinson as a plumber and heating engineer between 1944 and 1954, apart from a two-year break for National Service.  About half that time was spent in repairing boilers.  He was then employed as a foreman plumber and heating engineer by J Lindley & Co Ltd (“Lindleys”), between May 1954 and July 1968.  Lindleys employed between 10 and 12 plumbers and heating engineers.  A large proportion of their work was carried out on contracts for the defendants, the Leeds City Council, in connection with the repair of heating boilers in their schools, rates offices and other properties.
17.	For about half his time with Lindleys Mr Twohey worked on council properties.  Before he died he made a list of the local schools at which he worked.  (Two of these were privately owned schools).  At these schools he would remove the asbestos lagging to the boilers and pipework with a chipping hammer.  After he had carried out the necessary repairs, he would sometimes mix the asbestos he had removed with water and new asbestos, and re-apply this new asbestos covering to the boiler and pipes.  He took no precautions against the asbestos dust and fibres that were generated in this work.  The boilers were mostly in confined areas, many of them in cellars and basements, where the ventilation was either poor or non-existent.  A fellow worker, Mr Ball, said that when they first chipped away at the lagging, the asbestos was hard and crusty, but it turned into a powdery substance lower down, and this created a lot of dust. He sometimes had to leave the boiler house to get fresh air because the air there had become so full of dust.
18.	Mr Twohey then worked for four other employers, including the Ministry of Defence and two local health authorities.  He developed malignant mesothelioma in the autumn of 1988, and died in July 1989.  Mr Dyson and his fellow executor originally sued seven defendants, but they eventually limited their claim to the Leeds City Council, as the occupiers of the premises where he worked for much of his time with Lindleys.  The judge found that the council ought to have known of the dangers of asbestos dust from 1958 onwards, and there is no appeal against that finding.  The question whether the council is liable as occupiers is the only issue that arises on this appeal.
(vi)  Robert Pendleton
19.	Robert Pendleton was born in June 1938.  He was employed at various times between 1966 and 1989 by the four defendants and by other employers.  While he was employed by the four defendants he was exposed to asbestos dust, and there were periods of his employment by three other employers when he was also so exposed.
20.	This exposure resulted in his having bilateral calcified pleural plaques.  There was no dispute about liability and it was agreed that liability for the agreed general damages should be apportioned as to 7.44%, 1.55%, 5.57% and 52% between the four defendants, allowance being made for the periods when Mr Pendleton was exposed to asbestos by the three other employers who were not parties to this suit.  (For this approach to apportionment, see para 68 below).  Judgment was entered in default against the first defendants, but no further action was contemplated against them.  An agreed order for provisional damages was made against the other three defendants to cover the chance that Mr Pendleton might at some time in the future contract asbestosis or diffuse pleural thickening.  The issue the judge had to decide was whether the order for provisional damages should also cover the risk of his contracting mesothelioma (or asbestos-induced cancer), and this is the only issue on this appeal.
3.	Mesothelioma and Asbestosis: (i)  Mesothelioma
21.	It is now necessary to distinguish between mesothelioma and asbestosis.  Both diseases are caused by exposure to dust, but mesothelioma has been described, because of its aetiology, as an indivisible disease, whereas asbestosis has been described as a divisible, or cumulative, disease. This distinction is very important in this case.
22.	Mesothelioma arises when one of the mesothelial cells in the pleura is damaged and undergoes malignant transformation.  A tumour then develops from that single malignant mesothelial cell.  The precise mechanics of the disease are still not known, but it is received medical opinion that at least 90% of cases of mesothelioma result from exposure to asbestos. In this country 50 or 60 people suffer mesothelioma each year where there has been no history of identifiable exposure to asbestos dust, in contrast to 1,500 where there is such a history.  Although asbestos fibre types differ in their propensity to cause mesothelioma, there was no reliable evidence in any of the present cases pointing to exposure to one type of asbestos rather than another.
23.	It has been suggested that the initiating cause may be direct or indirect, or a combination of the two.  The cause is direct where damage is caused to the DNA of the affected cell by its interaction with an asbestos fibre or fibres - in Matthews it was suggested that a grating mechanism may be at work - or where there has been some interference with that portion of the DNA which controls the proliferation of the cell.  There are two possible indirect mechanisms.  The asbestos fibres may become engulfed by scavenger cells in the lungs called macrophages, which release chemical mediators which may bring about DNA damage or interfere with recovery mechanisms.  Alternatively, these chemical mediators may stimulate the proliferation of cells, increasing the chances of a malignant cell surviving and proliferating.  It is not known whether a single fibre or multiple fibres triggers the onset of malignancy: each situation is as likely as the other.  
24.	Doctors believe that the development of malignancy is a multi-stage process involving a sequence of perhaps six or seven genetic changes which result in a normal cell being transformed into a malignant cell.  Asbestos may have a part to play at one or more of these stages.  There is no evidence that the action of asbestos at one stage is more or less likely than action at more than one stage, or whether such actions are by one fibre or more than one.
25.	The risk that mesothelioma will occur increases in relation to the total dose of asbestos received. The severity of the sufferer’s condition and the resulting disability do not, however, vary with the dose of asbestos which caused it.  If there has been more than one employment involving asbestos exposure, there is no means of determining from which employment was derived the fibre or fibres which brought about the malignant transformation.  It is not now thought that the development of a mesothelioma is due to a process by which the totality of the asbestos load overwhelms the body’s defences by progressively “weakening” them until a mesothelioma develops.  The disease occurs typically more than 30 years after exposure to asbestos fibres, and it then takes about 10 years from its inception until the time when symptoms become evident.  There is no upper limit to the later period.  The disease is almost always fatal within two years of its appearance.
26.	It was therefore common ground on these appeals that it could not be said whether a single fibre of asbestos was more or less likely to have caused the disease, alternatively whether more than one fibre was more or less likely to have caused the disease.  In the latter event, it could not be shown that it was more likely than not that those fibres came from more than one source.  In other words, none of these scenarios could be proved on the balance of probabilities.  Similarly, it could not be proved on the balance of probabilities that any one man’s mesothelioma was caused cumulatively by exposure to asbestos dust in more than one employment.
(ii)  Asbestosis
27.	Mesothelioma is therefore an all or nothing disease.  It is thus different from asbestosis (or pneumoconiosis) which are cumulative diseases.  Mesothelioma is triggered off on a single unidentifiable occasion when one or more asbestos fibres initiate the process which leads ultimately, many years later, to the diagnosis of the disease.  Asbestosis is different.  There is a minimum dose of asbestos below which there is no risk that asbestosis will develop.  Above that minimum dose the severity of the condition, if it does develop, increases in relation to the total dose of asbestos inhaled.
28.	If follows that if asbestosis has resulted from more than one employment involving asbestos exposure it may reasonably be argued that the different periods of employment have contributed to the severity of the condition and the resultant disability approximately in proportion to the dose of asbestos each contributed to the total dose of asbestos received. We return to this topic in paragraphs 68-70 below.
4.	The causation caselaw: (i)  Bonnington Castings, Nicholson and Gardiner
29.	In Bonnington Castings Ltd v Wardlaw [1956] AC 613 a steel dresser developed pneumoconiosis from being exposed for eight years to silica dust in the foundry in which he worked.  There was one non-tortious cause of the excessive dust (the use of a pneumatic hammer which could not be fitted with dust extraction plant) and one tortious cause (the failure to keep the dust extraction plant on the swing grinders in the foundry free from obstruction).  
30.	The employers argued that they had demonstrated that on the balance of probabilities the disease had been caused by dust from the hammers and not from the swing grinders. Mr Wardlaw argued that the cause of his injury was not the emanation of the dust but its inhalation, and that of the dust inhaled the amount contributed by the swing grinders was not negligible.
31.	Lord Reid accepted at p 620 that a pursuer or plaintiff must prove not only negligence or breach of duty but also that on the balance of probabilities such fault caused or materially contributed to his injury.  He disapproved the earlier decision of this court in Vyner v Waldenberg Brothers Ltd [1946] KB 50 which had held that if an employer was found to have been in breach of a duty imposed by statute, the onus of proof shifted onto him to show that the breach was not the cause of his employee’s injury.
32.	Turning to the facts of the case, Lord Reid said at p 621 that the medical evidence showed that pneumoconiosis was caused by a gradual accumulation in the lungs of minute particles of silica inhaled over a period of years.  He said that the real question was whether the dust from the swing grinders materially contributed to the disease.  What was a material contribution must be a question of degree, and he thought that any contribution which did not fall within the exception “de minimis non curat lex” must be regarded as material.
33.	The House was not concerned with any argument to the effect that because pneumoconiosis was a cumulative disease an attempt should be made to apportion responsibility for the pursuer’s loss between the tortious and non-tortious sources of dust.  On the contrary, Lord Keith of Avonholm said at p 626 that prima facie the particles inhaled were acting cumulatively, and he thought the natural inference was that had it not been for this cumulative effect Mr Wardlaw would not have developed pneumoconiosis when he did and might not have developed it all.  In other words, he appears to have been treating pneumoconiosis as an indivisible injury. We return to this topic at paragraph 69 below.
34.	The logic of this decision was applied by the House of Lords the following year in Nicholson v Atlas Steel Foundry and Engineering Co Ltd [1957] 1 WLR 613.  In a similar foundry setting silica dust was being produced by a non-tortious cause, but the employers were at fault for providing inadequate ventilation.  Lord Cohen said at p 622 that they were admittedly not to blame for the generation of the cloud of dust, but that any failure to provide proper ventilation must lengthen the period during which the cloud remained intense.  It seemed to him to follow that this failure must increase the risk to which their workmen were exposed, and in those circumstances he thought that the evidence established that on a balance of probabilities the employers’ breach of duty caused or materially contributed to Mr Nicholson’s injury.
35.	In Gardiner v Motherwell Machinery and Scrap Co Ltd [1961] 1 WLR 1424 a workman who had been employed for three months in demolition work subsequently suffered from dermatitis.  His employers were at fault for not providing proper washing facilities.  He had never suffered from this disease before, and the conditions to which he was exposed at work were liable to cause the disease.  It was admitted that his original symptoms were typical of industrial dermatitis.
36.	There was an issue on the appeal as to whether he had contracted the disease from other causes.  Lord Reid said at p 1429 that in his opinion when a man who had not previously suffered from a disease contracted it after being subjected to conditions likely to cause it, and when he showed that it started in a way typical of disease caused by such conditions, he established a prima facie presumption that the disease was indeed caused by those conditions.  The presumption could be displaced in many ways, but Lord Reid was not satisfied that the employers had succeeded in displacing it on the facts of that case.
(ii)  McGhee
37.	McGhee v National Coal Board [1973] 1 WLR 1 was another case in which the House of Lords held that a tortious cause materially contributed to an injury for which there was also a non-tortious cause.  A workman who was used to emptying pipe kilns at a brickworks was sent to empty brick kilns where the working conditions were much hotter and dustier than those to which he was accustomed.  His employers failed, in breach of duty, to provide him with washing facilities after his work, and he cycled home caked with sweat and dust before he had the opportunity to wash.  He suffered extensive irritation of the skin three days later, and he was diagnosed to be suffering from dermatitis.
38.	The medical evidence showed that dermatitis was caused by repeated minute abrasions of the outer horny layer of the skin, followed by some injury to the underlying cells, the precise nature of which was still unknown.  If a man sweated profusely for a long period, the outer layer of his skin would be softened and become prone to injury, and if he then worked in a cloud of abrasive brick dust, considerable quantities of the dust would adhere to his skin.  Exertion would cause these particles of dust to injure the horny layer, exposing the tender cells below to injury or infection.  In some way not then understood dermatitis might result.
39.	If the skin was not thoroughly washed as soon as he ceased work, this process could continue for some considerable time.  Mr McGhee had to continue exerting himself after work by bicycling home while caked with sweat and grime, so that he would be liable to further injury until he could wash himself thoroughly.
40.	Washing the skin was the only practicable way of removing the danger of further injury.  The effect of such abrasion of the skin was cumulative in the sense that the longer a subject was exposed to injury the greater the chance of his developing dermatitis.  It was for that reason that immediate washing was well recognised as a proper precaution.  Neither of the medical experts was willing to say that washing after work would have made it more probable than not that Mr McGhee would have escaped dermatitis, and his own expert implied that in the present state of medical knowledge no doctor could make such an assertion in any circumstances.
41.	The Lord Ordinary and the First Division of the Court of Session dismissed Mr McGhee’s claim.  They held that he had to prove a causative connection between his injury and his employers’ breach of duty, and that this involved proving that it was more likely than not that the breach of duty caused the injury.  Merely to show that compliance with that duty would have materially reduced the risk of injury was insufficient: it was necessary to show that such compliance would on a balance of probabilities have avoided the injury.  The House of Lords unanimously allowed Mr McGhee’s appeal.  Five separate speeches were made, each giving different reasons but concurring in the result.
42.	Lord Simon of Glaisdale at pp 8B-9B applied Bonnington Castings, Nicholson and Gardiner.  He said that the first two of these cases established that where an injury was caused by two (or more) factors operating cumulatively, one (or more) of which factors was a breach of duty and one (or more) was not, in such a way that it was impossible to ascertain the proportion in which the factors were effective in producing the injury or which factor was decisive, the law did not require a pursuer or plaintiff to prove the impossible.  He would be entitled to damages for his injury if he proved on a balance of probabilities that the breach or breaches of duty contributed substantially to causing the injury.  If such factors so operated cumulatively, it was in his judgment immaterial whether they did so concurrently or successively.
43.	It is clear that when Lord Simon used the expression “this type of case” twice in a single paragraph (at 8D and 8F) he was referring to a case in which two or more factors operated cumulatively and it was impossible to disaggregate their individual effect.  In that type of case he said that a failure to take steps to bring about a material reduction of the risk involved a substantial contribution to the injury.
44.	Lord Kilbrandon also appears to have approached the medical evidence on the basis that the potential causes of the disease, non-tortious and tortious, were cumulative in effect.  The employers’ expert witness had accepted that a shower after work would materially reduce the risk to a man’s skin of injury from such working conditions, and he said that the Court of Session’s finding that the employers were in breach of duty could only have been because knowledge had to be imputed to them that if Mr McGhee’s body were to continue to be exposed to the dirt and sweat which were operating on him after he had finished work (being the only dirt and sweat a shower could have removed), it was more probable that he would contract the disease than if no shower had been taken (see p 9D-9G).
45.	He then applied the Bonnington Castings test.  Mr McGhee had proved that there was a precaution, neglected by the defendants, which, if adopted by them, would have made it less likely that he would have suffered the damage.  Lord Kilbrandon said at p 10B that he did not find it easy to say in the abstract where the possibility of the efficacy of the precautions shaded into the probability that they would have been efficacious.  But in a case where the actual chain of events in a man’s body leading up to his injury was not clearly known, but it was proved that the defendants knew that to take a precaution reduced the chance/risk/possibility/probability of contracting the disease, that the precaution was not taken and that the disease had supervened, it was difficult to see how they could demand more by way of proof of the probability that their failure caused or contributed to the physical breakdown.  
46.	Lord Salmon said at p 11G that he accepted that the burden rested upon the pursuer to prove, on the balance of probabilities, a causal connection between his injury and the defenders’ negligence.  It was not, however, necessary to prove that their negligence was the only cause of injury.  A factor, by itself, might not be sufficient to cause injury but if, with other factors, it materially contributed to causing injury it was clearly a cause of injury. He regarded the identification of the cause of an event to be essentially a practical question of fact which could best be answered by ordinary common sense.  In the circumstances of Mr McGhee’s case it seemed to him (at p 11H) unrealistic and contrary to ordinary common sense to hold that the negligence which materially increased the risk of injury did not materially contribute to causing the injury.  Lord Salmon seems to have regarded the results of the failure to wash not as a cause which could have operated on its own, but as a cause which could have added cumulatively to the effect of the heat and dirt at work.
47.	He suggested at p 10G-H that the true view was that, as a rule, when it was proved on the balance of probabilities that an employer had been negligent and that his negligence had materially increased the risk of his employee contracting an industrial disease, he was liable in damages to his employee if he did contract that disease, notwithstanding that he was not responsible for other factors which had materially contributed to the disease.  He did not find the attempts to distinguish Bonnington Castings and Nicholson from Mr McGhee’s case at all convincing.
48.	Lord Wilberforce’s minority view started a hare running which was eventually checked by the House of Lords in Wilsher v Essex Area Health Authority [1988] 1 AC 1074.  He, too, thought (at p 5H) that the medical evidence showed that Mr McGhee’s dermatitis resulted from a combination, or accumulation, of two causes.  He considered that it was a sound principle that where a person had, by breach of a duty of care, created a risk, and injury occurred within the area of that risk, the loss should be borne by him unless he showed that it had some other cause.  In other words, in those circumstances the onus of proof would shift to the defender to show that his negligence had not caused the injury.  This approach was disapproved by the House of Lords in Wilsher.
49.	On the hearing of these appeals Mr Langstaff concentrated most of his attention on Lord Reid’s speech, and in particular a critical passage at pp 4E-5B.  Lord Reid said that the evidence did not show just how dermatitis of this type began.  It suggested two possible mechanisms.  It might be that an accumulation of minor abrasions of the horny layer of the skin was a necessary precondition for the onset of the disease.  He was inclined to think that the evidence pointed that way, but he could not say that this was proved.  If it were, then the case would be indistinguishable from Bonnington Castings.
50.	It might, however, be that the disease started at one particular abrasion (which could have been caused by the processes at work when Mr McGhee bicycled home), and then spread, so that multiplication of abrasions merely increased the risk of its occurrence.  
51.	He thought in these circumstances that in cases like this the courts had to take a broader view of causation.  He said (at pp 4G-5B):
“The medical evidence is to the effect that the fact that the man had to cycle home caked with grime and sweat added materially to the risk that this disease might develop.  It does not and could not explain just why that is so.  But experience shows that it is so.  Plainly that must be because what happens while the man remains unwashed can have a causative effect, though just how the cause operates is uncertain.  I cannot accept the view expressed in the Inner House that once the man left the brick kiln he left behind the causes which made him liable to develop dermatitis.  That seems to me quite inconsistent with a proper interpretation of the medical evidence.  Nor can I accept the distinction drawn by the Lord Ordinary between materially increasing the risk that the disease will occur and making a material contribution to its occurrence.
There may be some logical ground for such a distinction where our knowledge of all the material factors is complete.  But it has often been said that the legal concept of causation is not based on logic or philosophy.  It is based on the practical way in which the ordinary man’s mind works in the everyday affairs of life.  From a broad and practical viewpoint I can see no substantial difference between saying that what the defender did materially increased the risk of injury to the pursuer and saying that what the defender did made a material contribution to his injury.”
(iii)  Thompson, Bryce and Wilsher
52.	In Thompson v Smiths Shiprepairers (North Shields) Ltd [1984] QB 405 Mustill J considered McGhee in the context of a contention that men who had been subjected to excessive noise in ship-building yards and ship-repair yards should recover 100% compensation for their irreversible hearing loss, even though part of their hearing loss was attributed to other causes, including the ageing process.
53.	At p 442C-E he said he believed that McGhee was authority for two propositions.  The first, based on Bonnington Castings and Nicholson, was that where there were two or more causes concurrent in effect if not necessarily in time, any contribution by the defendants’ wrongdoing greater than de minimis was sufficient to establish causation.  The second, which he said broke new ground, was to use the fictional device of treating the proof that the breach had increased the risk of the disease as if it were proof that the breach had actually caused the disease, as a means of bridging the “evidential gap” created by the absence of proof that the breach was at the very least a sine qua non.
54.	While explaining why this second proposition was of no help to the plaintiffs in Thompson, (because that case was not concerned with excessive noise and injury which was a proved fact), Mustill J referred at p 443B to what he described as the “McGhee principle”.
55.	The same judge sought to clarify “the principle applied by the House [of Lords] in McGhee” in Wilsher v Essex Area Health Authority [1987] QB 720, 771-2.  A premature baby was found to be suffering from retrolental fibroplasia (“RLF”), a condition of the eyes which results in blindness.  He was born prematurely and very nearly died in the first few weeks of his life during which he passed through a series of crises.  There were six possible causes of his RLF including the very fact of premature birth itself.  One of those possible causes was the toxic effect of a sufficiently high level of oxygen in the arterial blood during the first two days of his life when there was a substantial period of time during which hospital staff had negligently allowed the level of oxygen in the arterial blood to remain above an accepted level of safety. 
56.	The trial judge (Peter Pain J) did not find that excess oxygen had caused the RLF.  Instead, he applied a rule he had invented in his own earlier judgment in Clark v MacLennan [1983] 1 All ER 416, 427, where he had derived from McGhee a proposition that where there was a situation in which a general duty of care arose and there was a failure to take a precaution, and where that very damage occurred against which the precaution was designed to be a protection, then the burden of proof shifted to the defendant to disprove both negligence and causation.
57.	The Court of Appeal restored the conventional rule that the burden lay on the plaintiff to prove negligence, but the majority upheld the judgment on causation.  Mustill LJ, with whom Glidewell LJ agreed, said at pp 771-2 that reading all the speeches in McGhee together, the principle applied in that case seemed to him to amount to this:
“If it is an established fact that conduct of a particular kind creates a risk that injury will be caused to another, or increases an existing risk that injury will ensue; and if the two parties stood in such a relationship that the one party owes a duty not to conduct himself in that way; and if the party does conduct himself in that way; and if the other party does suffer injury of the kind to which the risk related; then the first party is taken to have caused the injury by his breach of duty, even though the existence and extent of the contribution made by the breach cannot be ascertained.”
58.	Sir Nicolas Browne-Wilkinson V-C disagreed.  He, too, referred to “the principle in McGhee” [at p 466E], but he said that it would constitute an extension of that principle if it was applied, not to a case in which there was only one possible agent which could have caused the injury, but to a case where there were a number of different agents which could have caused the injury.  He noted that in McGhee Lord Reid and Lord Wilberforce had accepted that their decision was based not on logic but on common sense or public policy.  He did not consider it right to extend further an illogical decision taken on the grounds of policy to cover the present case, where the defendants might well not have caused the injury, and where the steps they ought to have taken would not have avoided the injury if in fact the cause of the plaintiff’s RLF was one of the other candidates.
59.	In Bryce v Swan Hunter Group plc [1987] 2 Lloyd’s Rep 426, Mr Bryce had died of mesothelioma after working in the shipyards for many years.  Phillips J found that although the additional exposure to asbestos dust attributable to breaches of duty by the defendants was significant in itself, it was less in degree than the exposure that he would in any event have experienced during his working life.  It was not possible for the plaintiff to prove on the balance of probabilities that the additional fibres inhaled by Mr Bryce as the result of breaches of duty by either of the defendants were a cause of his mesothelioma.  It was equally impossible for either of them to prove on the balance of probabilities that their breaches of duty were not at least a contributory cause of Mr Bryce contacting that disease.
60.	Phillips J held that in these circumstances the plaintiff could successfully invoke “the principle in McGhee” as identified by the Court of Appeal in Wilsher.  Whether the defendants’ breaches of duty merely added to the number of possible initiators of mesothelioma in Mr Bryce’s lungs, or whether they also produced a cumulative effect on the reduction of his body’s defence mechanism (a theory not advanced by any of the doctors in the cases with which we are now concerned), they increased the risk of his developing mesothelioma.  Because he did in fact develop mesothelioma, each of the defendants must be taken to have caused the mesothelioma by its breach of duty.
61.	When Wilsher reached the House of Lords ([1988] 1 AC 1074), Lord Bridge made the only speech.  He disapproved (at p 1087G) Lord Wilberforce’s suggestion that in a case like McGhee the burden of proof of causation could be reversed.  He considered that the decision of the majority in McGhee was underpinned by a process of inferential reasoning along the following lines.  Although the doctors could not identify the process of causation scientifically – the “innocent” dust and the “guilty” dust might both have contributed to the cause of the disease or, theoretically at least, one or other of them might have been its sole cause – there seemed to be nothing irrational in drawing an inference, as a matter of common sense, that the consecutive periods when brick dust remained on the body probably contributed cumulatively to the causation of the disease.
62.	After analysing the speeches of the majority in McGhee, Lord Bridge said in emphatic terms that that case laid down no new principle of law whatever.  The majority had adopted a robust and pragmatic approach to the undisputed primary facts, and it was fruitless to attempt to extract from it some esoteric principle which in some way modified the nature of the burden of proof of causation that rests on a plaintiff.  Lord Bridge expressly approved Sir Nicolas Browne-Wilkinson V-C’s approach in his dissenting judgment in the Court of Appeal.
63.	Lord Bridge ended his speech by referring to the shortcomings of a system in which the victim of some grievous misfortune would recover substantial compensation or none at all according to the unpredictable hazards of the forensic process.  He repeated that the law required proof of fault causing damage as the basis of liability in tort, and concluded by saying that the House of Lords would do society nothing but disservice if it made the forensic process still more unpredictable and hazardous by distorting the law to accommodate the exigencies of what might seem hard cases.
(iv)  Some Commonwealth cases
64.	Before coming to the last English case to which we wish to refer, it is worth looking at the experience of two other common law countries which are grappling with problems caused by the difficulties of proving causation in certain types of complex case.  In Farrell v Snell (1990) 72 DLR (4th) 289 Sopinka J, giving the judgment of the Supreme Court of Canada, disapproved earlier Canadian cases in which, purporting to follow McGhee, the onus of proof of causation had been shifted to the defendant once a relevant breach of duty had been proved.  He commented, however, at p 300 that the dissatisfaction with the traditional approach to causation stemmed from its too rigid application by the courts in many cases.  He referred favourably to Lord Salmon’s approach in McGhee, and said that where facts lay particularly within the knowledge of the defendant, very little affirmative evidence on the part of the plaintiff would justify the drawing of an inference of causation in the absence of evidence to the contrary.
65.	In Australia both the full court of the Supreme Court of Victoria and the New South Wales Court of Appeal have denied compensation to mesothelioma victims where they had a history of exposure to more than one source of asbestos.  See Wintle v Conaust (Vic) Pty Ltd [1989] VR 951 and Wallaby Grip (BAE) Pty Ltd v MacLeay Area Health Service (CA 40620/97), a case in which the High Court of Australia later refused permission to appeal.  In the second of these cases Beazley JA set out what she described as eight well known principles of causation:
i)	A plaintiff must establish that his or her injuries are “caused or materially contributed to” by the defendant’s wrongful conduct;
ii)	Proof of default by the defendant followed by injury of the plaintiff is insufficient to establish causation;
iii)	If the defendant’s negligence cannot be causally linked to the particular risk, the plaintiff must bear the loss;
iv)	A causal connection is established if it appears that the plaintiff would not have sustained his or her injuries had the defendant not been negligent;
v)	The impossibility of excluding a factor as a cause of injury does not establish that factor as the  cause of that injury;
vi)	A plaintiff must show more than that it is possible that injury was caused by the defendant;
vii)	One or more defendants may be liable if each has been shown to have negligently exposed a plaintiff to the risk of contracting the fatal disease.  It will be sufficient to establish liability against each if their several acts caused or contributed materially to the onset of mesothelioma;
viii)	A material increase in the risk of injury by a defendant is not legally equated with a material contribution to the injury by a defendant.  However, in some circumstances if it were proved that the defendant did materially increase the risk of injuring the plaintiff then the court might infer causation, ie that the defendant’s negligence ‘materially contributed’ to the injury.
66.	She went on to say that a number of principles had emerged in the cases to assist proof of causation where a plaintiff is suing multiple defendants in circumstances where it was unclear which defendant(s) might be liable.  One of these principles was that the trier of fact was entitled (indeed encouraged) to take a “robust and pragmatic” approach to causation; causation would not be defeated by the absence of evidence showing precisely how an event had occurred.  Another principle was that slight evidence might suffice to persuade the trier of fact that liability might be sheeted home to a defendant where the facts were particularly within the knowledge of that party.
67.	The juxtaposition of Beazley JA’s seventh and eighth propositions are of course at the centre of the present appeal.  Curiously, the same judge was a party to a decision in the same court in a mesothelioma case five days later where on different medical evidence (which was also different from the medical evidence before us in these six appeals) the court held that the evidence had established that two different defendants had both exposed the plaintiff to asbestos dust in a way which materially contributed to the disease he had suffered.  See E M Baldwin & Son Pty Ltd v Plane [1999] Aust Torts Rep 81-499.  She commented at 65, 622 that the differences of opinion which had emerged in recent mesothelioma cases were, for the most part, less related to questions of principle and more attributable to conflicting views of the primary facts, and in some instances, at least, to the conclusions to be drawn from expert evidence.
(v)  Holtby
68.	In recent years a practice grew up among employers’ liability insurers to accept liability for asbestosis or mesothelioma on a time exposure basis. For example, if their insured employed the claimant for three years out of the 30 years in which he was negligently exposed to asbestos dust at his various places of work, they would agree to bear 10% of the total liability.  The correctness of this approach was disputed by a claimant in Holtby v Brigham & Cowan (Hull) Ltd [2000] 3 All ER 421 when he challenged the decision of a trial judge to reduce the compensation for his asbestosis by 25% because exposure to asbestos dust with other employers had contributed cumulatively to his disease.  
69.	In Holtby  Stuart-Smith LJ, with whom Mummery LJ agreed, observed (at para 14) that it was never argued in the Bonnington Castings case that the defendants were only liable to the extent of their material contribution to the disease (see also our comment at para 33 above).  He rejected a contention, based on the judgment of the US Court of Appeals Fifth Circuit in Borel v Fireboard Paper Products Corp 493 F 2d 1076 (1973), to the effect that where several defendants were each shown to have caused some harm, the burden of proof shifted to each of them to show what portion of the harm he had caused.  He said (at para 20):
“The question should be whether at the end of the day and on consideration of all the evidence, the claimant has proved that the defendants are responsible for the whole or a quantifiable part of his disability.  The question of quantification may be difficult and the court only has to do the best it can using its common sense, as Lord Salmon said in the passage cited.  Cases of this sort, where the disease manifests itself many years after the exposure, present great problems, because much of the detail is inevitably lost.  I can see that in Borel’s case, where the defendants were manufacturers as opposed to employers, the position may be particularly difficult.  But in my view the court must do the best it can to achieve justice, not only to the claimant but to the defendant, and among defendants.”
70.	This approach is clearly legitimate in cases of disease or disability where medical evidence shows that the effect of the defendants’ negligence can be treated as cumulative in the sense that the greater the period (or intensity) of exposure, the greater the resultant disease or disability.  Asbestosis and pneumoconiosis fall into this category of case.  So, as Stuart-Smith LJ observed in Holtby (in para 22), does hearing loss, although there the process of just apportionment may be more complex.
71.	The question we have to decide on these appeals is whether this approach (or, as the claimants argued, an approach which might leave a single employer liable for 100% of the injury where no other viable or insured employer can be identified) is appropriate in the case of an indivisible disease like mesothelioma, where medical evidence cannot say that on the balance of probabilities any particular exposure to asbestos dust at any particular time materially contributed to the disease from which the claimant suffered.  Before turning to consider this question it is first necessary to summarise the effect of the decisions of the trial judges in the three causation cases of Fairchild, Fox and Matthews.
5.	The judgments on causation in the courts below: (i) Fairchild
72.	In Fairchild, Curtis J said that if the matter was free from authority, he would unhesitatingly, though reluctantly, hold that the claimant was unable to establish on the balance of probabilities that the breaches of duty by either defendant (if proved) caused or made a material contribution to the cause of her husband’s mesothelioma.  He distinguished the situation in Holtby because there was no question of a cumulative effect of the successive exposures to asbestos.
73.	He said that it would be wrong to find that they had both contributed to the disease, since it was equally probable that only one of them did.  It could not be determined when a fibre triggered off the initiating causes of the malignancy, or whether one fibre or more than one had initiated the disease, or whether there was any material difference between the levels of exposure alleged to be the responsibility of each defendant.
74.	He then considered the authorities and found nothing in them to deflect him from these views.  In particular he was of the opinion that in the light of the decision of the House of Lords in Wilsher no reliance could safely be placed on a dictum of Mustill LJ in the Court of Appeal in that case (see para 57 above) or on the judgment of Phillips J in Bryce.  The law still required a claimant to prove that the defendant’s negligent acts did in fact cause, or materially contribute, to his injury and not merely to the risk of injury.
(ii) Fox
75.	Judge Mackay, sitting as a high court judge in Liverpool, had the benefit of Curtis J’s judgment in Fairchild when he decided the case of Fox.  Although the legal submissions he received were slightly different, he reviewed the effect of the same authorities and came to the same conclusion as Curtis J.
(iii) Matthews
76.	Mitting J, too, had the benefit of Curtis J’s judgment.  He arrived at a different result.  He was encouraged by Lord Bridge’s speech in Wilsher to adopt a robust and pragmatic approach to the question of causation where the precise aetiology of a disease was unknown.  Adopting that robust approach, his firm conclusion was that Mr Matthews’s exposure to asbestos fibres in the employment of the two defendants did materially contribute to, and so cause, his mesothelioma.  Like Lord Reid in McGhee (see para 51 above), he could see no substantial difference between saying that what the defendants did materially increased the risk to the claimant and saying that when they did make a material contribution to his injury.  
77.	He said that his chain of reasoning sounded remarkably like that expounded by Mustill LJ in Wilsher.  When Mustill LJ’s approach (see para 57 above) was applied to facts on which there was only one possible cause, it was no more than a restatement of the robust approach to causation found in McGhee and was still good law.  Mitting J apportioned liability equally between the two defendants.  If his judgment is upheld, there is no appeal against that apportionment.
6.	Causation: the arguments
78.	Mr Langstaff, who appeared for the unsuccessful claimant in Fairchild, based his arguments on five main submissions.  He said that his client had proved that the alleged causal agent (asbestos) had resulted in injury (mesothelioma).  She was not required by the law to go further and establish the precise causal mechanism which causes asbestos inhalation to develop into mesothelioma.  Where the substance which caused an injury was known (but not where it might be a number of rival substances), the principles found in the decision of the House of Lords in McGhee would determine whether the claimant established liability.  Where medical knowledge was imperfect, then whether causation was or was not proved often involved the application of robust common sense by the trial judge.  Finally, he argued that the factual circumstances of this case were indistinguishable from McGhee.  
79.	He invited us to consider a situation in which a workman was enveloped in a cloud of asbestos dust which was being caused simultaneously by people stripping asbestos lagging at one end of the room and different people mixing and applying new lagging at the other, and where there was no other identifiable cause of the mesothelioma.  He suggested that a court would not waste time speculating whose fibre had initiated the malignancy: it would hold those responsible for each operation equally to blame.  It would not acquit them both.  So, too, if the exposure to the strippers was in Week 1 and the exposure to the laggers in Week 2, and so on.  He suggested that it was open to us to apply the same robust common sense to a lifetime of exposures, where it was known to be impossible for a claimant to prove whose fibre or fibres had caused the malignancy, or the different stages of the transformation of a healthy cell into a malignant cell. He suggested, quoting an expression Mustill J used in the Thompson case, that the “guilty” fibres should be treated as two or more causes which were concurrent in effect, if not necessarily in time.
80.	He urged us not to over-refine our analysis of causation, given that it was impossible to identify the “guilty” fibres.  The practice of apportioning responsibility on a time-exposure basis had worked perfectly well without any discernible difficulty for a number of years.  Even if, which he disputed, he was wrong in submitting that McGhee established a principle we should follow, he said that in that case and the other three Scottish cases the House of Lords had lit a policy beacon which sent a message that courts should be ready to find for claimants in circumstances like these where there might be an evidential gap to bridge between the defendants’ admitted or proved breach of duty and the claimant’s surrender to a disease associated in a causal sense with the breach of duty in question.  He said that the course he urged on us was a realistic one, given that we should not waste time engaging in what he described as sub-atomic speculation, requiring proof of what could not be proved.
81.	He showed us how before Curtis J’s judgment in Fairchild medical experts equated a material increase in risk with a material contribution to the causation of a disease.  Dr Hind, who gave evidence for the second defendant in Matthews, told Mitting J that doctors talk about “cause” rather than “causation”.  Dr Hind admitted that he had often said in his reports in the past that the exposures to asbestos had caused the mesothelioma.  He had left it to the lawyers to figure out which employer should bear which percentage of the cost.  Dr Rudd, who gave evidence for a number of the claimants in these cases, said in his report in the Matthews case:
“In consideration of causation of a particular mesothelioma medical science does not take a narrow mechanistic view, ie that the disease was caused only by the fibre or fibres which brought about the malignant transformation of the particular mesothelioma cell, any more than it takes the view that a lung cancer was caused only by the particular molecule or molecules of tar from one or more cigarettes which actually brought about the malignant transformation of a particular bronchial epithelial cell to a lung cancer cell.  Rather, when it is not possible to have precise mechanistic knowledge of the mechanism of malignant transformation, medical science takes the view, on the basis of epidemiological evidence, that all factors which contributed to the risk that malignancy would occur contributed to causation of the malignancy. Hence, all asbestos fibres inhaled are considered to have contributed to causation of a mesothelioma in the same way that all cigarettes smoked  are considered to have contributed to causation of a lung cancer.”
82.	Dr Rudd went on to say that in the Fairchild case it would have been in accordance with the evidence and with the medical approach to causation of disease to reach the conclusion that both sources of exposure (Meanwood Baths and Waddingtons) contributed to the disease.  In the Matthews case he had agreed with Dr Hind that each of the three main exposures contributed to the risk that Mr Matthews would develop mesothelioma.  On the basis of the usual medical approach to the causation of disease, the appropriate conclusion was that each of those exposures materially contributed to the causation of his mesothelioma.
83.	Mr Langstaff argued that it was legitimate to equate the creation of a material increase in risk with a material contribution to the cause of a disease in a situation where medical science had not yet developed to the extent that one could say with certainty how an agent like asbestos caused a result, although one could say with confidence that it did.  In this sense this case was different from Wilsher, where nobody knew what caused the boy’s RLF. 
84.	He said that the logic adopted by Lord Reid in McGhee to bridge the evidential gap and enable causation to be established did not depend on the existence of a single employer/potential tortfeasor.  According to that logic an employer might be being held liable for something which no breach of duty on his part had in fact caused (viz if the damage had in fact been complete by the time Mr McGhee stopped work, and before he cycled home).
85.	Mr Langstaff submitted that if by this route a tortfeasor was identified, it would be liable for the whole extent of the disease, because mesothelioma was an indivisible injury.  It would then have a right to claim contribution from others.  If part of the exposure occurred when the claimant was self-employed, he argued that a plea of contributory negligence was available.  He said that McGhee was on all fours with the present case.  Lord Reid and Lord Wilberforce had filled the evidential gap, although accepting that it was not logical to do so.  Lord Simon and Lord Kilbrandon had found causation established on Gardiner principles, and Lord Salmon had arrived at his result by regarding the problem as a practical question of fact which could best be answered by ordinary commonsense.
86.	He accepted that it would be necessary to regard the different exposures as “cumulative” in the sense that the longer the subject was exposed to injury, the greater the chance of his developing the disease.  He argued that material contribution to risk should amount to material contribution to injury in those cases where there is no knowledge or means of knowledge which enables the fact-finder to move from risk to contribution.  In those circumstances it is legitimate to bridge the evidential gap by saying that one equates to another.
87.	At the centre of his submissions was the argument that policy implications enabled the court to evaluate the force of the rival arguments as to causation and the application of the robust commonsense approach which this consideration involved.  If the tort system is to fulfil its function in preventing risks to health and safety being taken, it ought to provide compensation in a situation where such risks occur and their occurrence is in breach of duty, where the persons responsible for that breach are all before the court, and where there is no reason to excuse them from the financial consequences.  The person on the London Underground would regard it as thoroughly unfair and unjust if this did not happen.
88.	Mr Allan QC, who appeared for the claimants in the Fox and Matthews cases, supplemented Mr Langstaff’s arguments with brief submissions of his own.  He said that where medical science cannot explain how asbestos dust brings about the mutation of a cell, it was wholly unrealistic to require a claimant to prove the impossible.  People who suffer from occupationally induced mesothelioma usually do so after they have inhaled many millions of fibres, and it made no sense to focus on the role of the single fibre.
89.	Denial of liability would be unjust if a claimant could not recover when subjected to a single concurrent exposure of “guilty” and “non-guilty” dust, or if the only reason why he could not recover was that ownership of his employers’ business had changed while he was employed by it.  In most cases it would not be a satisfactory solution for the court to try and identify a majority exposure.  He suggested that once it was recognised that every tortfeasor should compensate the injured claimant in respect of that loss or damage for which he should justly be held responsible, the metaphysics of causation could be kept in their proper place.  Once liability had been established for this indivisible injury there could be no question of an apportionment (see Dingle v Associated Newspapers Ltd [1961] 2 QB 162, 188-9).
90.	There would be no injustice to defendants if the court were to adopt the approach to causation which had been adopted by parties in mesothelioma cases both before and after the decision of the House of Lords in Wilsher.  The solution the court arrived at ought to make sense to ordinary people.  His client Edwin Matthews, who is still alive, finds it difficult to understand why he cannot recover damages given that both defendants were in gross breach of the duties they owed him (see paras 11-12 above) and that he had got the disease.
91.	Mr Stephen Stewart QC, who appeared for Waddingtons in the Fairchild case, bore the main burden of the defendants’ response to these submissions.  Mr Taylor, for the Leeds City Council in that case, was content to adopt Mr Stewart’s submissions.  We received brief supplemental submissions from Mr Owen QC, who appeared for both defendants in the Matthews case, and even briefer submissions from Mr Wilkinson QC, for the defendants in the Fox case.
92.	Mr Stewart reminded us of the effect of the agreed evidence.  It was just as likely that a mesothelioma was initiated by a single fibre as that it was initiated by more than one fibre.  It was just as likely that different fibres were involved at each of the six or seven stages of genetic change as that no further fibre was involved at those stages.  None of the medical witnesses in these cases subscribed to the “total fibre burden” theory mentioned by Phillips J in Bryce (see para 60 above).  It was just as likely that a claimant’s “guilty” fibre came from his 10% risk of developing his disease from background exposure as that it came from any period of occupational exposure which occurred at least ten years before the onset of his symptoms.  This was a type of case in which nothing could be proved on the balance of probabilities.  Out of the thousands of millions of asbestos fibres these men may have inhaled during a working lifetime, nobody could ever say on the balance of probabilities which fibre, or which fibres, were responsible for causing or materially contributing to their mesothelioma.
93.	These cases were different from McGhee.  In McGhee there was no doubt that the causative agent was the dust which got on Mr McGhee’s skin from a day’s work for his employers at an identifiable brick kiln. In Fairchild nobody knew whether the injurious fibre or fibres came from Mr Fairchild’s work at Waddingtons (whether before or after the building at which he worked became a factory), or at the Meanwood Baths, or during his roofwork for Slacks, or while handling the asbestos-lined ovens for his first employers, or from other occupational exposure to asbestos, or from background exposure.
94.	Mr Stewart reminded us of two authoritative statements of the circumstances in which it is legitimate for a court to draw inferences.  In Richard Evans & Co Ltd v Astley [1911] AC 674 Lord Robson said at p 687:
“What precise intention [the deceased workman] had in his mind is, of course not now susceptible of direct proof, and the court must look at all the circumstances to see if they give rise to a reasonable and definite inference on the matter in question.  If they give rise to conflicting inferences of equal degrees of probability, so that the choice between them is mere matter of conjecture, then the applicant has failed to prove her case.”
95.	In the Australian case of Jones v Dunkel (1958-9) 101 CLR 298 Kitto J said at p 305:
“One does not pass from the realm of conjecture into the realm of inference until some fact is found which positively suggests, that is to say provides a reason, special to the particular case under consideration, for thinking it likely that in that actual case a specific event happened or a specific state of affairs existed.”
96.	Mr Stewart said that an inference can only be drawn, as in McGhee, in the absence of any other evidence implicating some other causal agent or some other potential tortfeasor (see Sir Nicolas Browne-Wilkinson V-C’s approach, approved by the House of Lords in Wilsher).  Here there was plenty of other evidence which precluded the making of an inference that any particular defendant was responsible for the “guilty” fibre or fibres.  Even if the theory of a multiple fibre causation was adopted, it would be necessary to show that at least one of the “guilty” fibres came from a particular defendant.
97.	It would be wholly unjust, he said, to treat this as an indivisible injury and then use an “evidential gap” inference to hold a single defendant who happened to be before the court 100% liable for the claimant’s mesothelioma.  In Fox, for instance, the defendants were Mr Fox’s employers for only a short part of his working life’s exposure to asbestos dust.  In Fairchild, neither of Mr Fairchild’s relevant employers were worth suing (if still identifiable), and if Mr Stewart’s clients won on the occupiers’ liability part of the appeal, the period of their potential Factories Act liability covered only a small part of Mr Fairchild’s total exposure to asbestos dust.
98.	It was noteworthy, he said, that when junior counsel pleaded the Fairchild case and opened it to the judge, his client’s case was presented on the basis that he could not prove whether it was a fibre or fibres inhaled at any particular place of employment which caused either the initial mutation of the cell or any of the subsequent genetic defects which led to its transformation into a malignant cell.  Phillips J had reached the same conclusion in the Bryce case.  He had only found himself able to enter judgment for the plaintiff by using the technique which was disapproved by the House of Lords in Wilsher.
99.	He reminded us, too, that Mitting J had only been able to find for Mr Matthews after he had taken comfort from a passage in Mustill LJ’s judgment in Wilsher which did not survive the House of Lords decision in that case.  It was not open to apply a Gardiner presumption in these cases, because there were plenty of other candidates as potential tortfeasors.  If recourse was to be had to common sense, he said that Dr Hind’s approach in Matthews had much to commend it.  If Mr Matthews had been his patient and told him the story of his working life, and then asked him when his mesothelioma had been caused, Dr Hind would have replied that it was impossible to say.  It could have been the first employer, or the second, or the third, or all three, or a combination of two of them.
100.	Mr Owen took us back to the House of Lords cases leading up to and including McGhee.  He said that if the medical evidence had shown that the development of the disease was part of a cumulative process, the court might legitimately infer that each exposure to “guilty” dust materially contributed to the causation of the disease, but in the present type of case that inference simply was not available.  Proof that one of the tortfeasors failed to take a preventative measure was no evidence as to which of them caused the injury.  In Mr Matthews’s case two of the three most significant candidates were before the court, but there were four other possible candidates.  He supported Mr Stewart’s argument to the effect that in McGhee there was no doubt that the employers’ brick dust caused the disease.  Here there was no doubt that asbestos was the causative agent, but there was plenty of room for doubt as to whose asbestos was responsible.
101.	Mr Wilkinson adopted all these arguments on behalf of his clients in the Fox case.  He said that all the expert evidence tended to the same conclusion.  It was impossible to make the causal connection on the balance of probabilities.  It was therefore not legitimate to infer it: see Rhesa Shipping Co SA v Edmunds [1985] 1 WLR 948, 957H.
7.	Conclusion : Causation
102.	Much as one would like to accommodate the arguments for the claimants, in our judgment they contained an inherent illogicality.  They knew that they could not prove on the balance of probability which period of exposure caused or materially contributed to the cause of the mesothelioma.  They knew that it was a matter of chance which defendant might survive in a form worth suing so long after the event.  In Fairchild none of the relevant employers were available.  In Fox there was only one, because the nature of the National Dock Labour Scheme precluded the identification of any other employer during his lifetime of work at the docks.  In Matthews only two out of the three most likely candidates were available.  So far as Waddingtons are concerned, if they are only liable for the Factories Act exposure during Mr Fairchild’s maintenance visits, the period of “guilty” exposure becomes even smaller.  Yet Mr Langstaff and Mr Allan argued that because mesothelioma is an indivisible injury, once one tortfeasor is brought before the court, it will be notionally liable, on the balance of probabilities, for the whole of the claimant’s injury.
103.	In our judgment, this leap over the evidential gap not only defies logic but is also susceptible of unjust results. It may impose liability for the whole of an insidious disease on an employer with whom the claimant was employed for quite a short time in a long working life, when the claimant is wholly unable to prove on the balance of probabilities that that period of employment had any causative relationship with the inception of the disease.  This is far too weighty an edifice to build on the slender foundations of the McGhee case, and Lord Bridge has told us in Wilsher that McGhee established no new principle of law at all.  If we were to accede to the claimants’ arguments, we would be distorting the law to accommodate the exigencies of a very hard case.  We would be yielding to a contention that all those who have suffered injury after being exposed to a risk of that injury from which someone else should have protected them should be able to recover compensation even when they are quite unable to prove who was the culprit.  In a quite different context Lord Steyn has recently said in Frost v Chief Constable of Yorkshire [1999] 2 AC 455 that our tort system sometimes results in imperfect justice, but it is the best the common law can do.
104.	In our judgment, what Lord Reid said in McGhee at pp 4G to 5B, in the passage of his speech which forms the basis of Mr Langstaff’s argument, must be read in the context of that case. There was only one causative agent, brick dust, and only one possible tortfeasor, Mr McGhee’s employer. In that situation Lord Reid was prepared to find  causation established in the absence of scientific proof. Lord Bridge in Wilsher has made it clear that the same technique cannot be used where there is more than one causative agent. It seems to us that for the same reasons the same technique cannot be used where there is more than one tortfeasor, unless of course the evidence establishes, on the balance of probabilities, that the disease was caused by cumulative exposure. 
105.	To attempt to extend what Lord Reid said to the present situation would also offend against the principle established in Hotson v East Berkshire Area Health Authority [1987] AC 750. Whilst it can be properly said that each tortious exposure to asbestos dust increased the employee’s risk of contracting mesothelioma, the claim in each case is not based on an increased risk, or to put it another way, on the loss of a chance of survival. The disease has, save in Pendleton, struck. The only damages that can be claimed are for contracting the disease. Until the disease develops, the employee does not know he has an injury capable of giving rise to a cause of action. Once it does develop, he has to establish on the balance of probability that the particular tortfeasor caused the disease. And, as we have explained, none of the claimants in the present cases can establish this.
106.	During the course of the hearing we heard some argument about the possible effect of the Pneumoconiosis etc (Workers’ Compensation) Act 1979.  We did not hear sufficient argument to enable us to know whether any of the mesotheliomas with which this litigation was concerned fell within the ambit of that statutory scheme.  Nor did we hear sufficient argument to enable us to form a view whether this Act, which is predicated on the assumption that the worker in question had always possessed “relevant employers” (against whom he might have or might have had a claim for damages in respect of his disablement and whom he might have sued if they had not all ceased to carry on business), applies in the case of a worker who has no relevant employer at all because he cannot establish causation against any of them.
107.	It is sufficient to say that if people like Mr Matthews do have a claim under the Act (which we were told would amount to a maximum of £31,500 in his case) the cost to the exchequer may run into tens of millions of pounds each year on the basis that there are about 1,500 mesothelioma sufferers each year whose disease is attributable to occupational exposure.  If they do not, these cases have revealed a major injustice crying out to be righted either by statute or by an agreed insurance industry scheme.
108.	For the sake of completeness we would add that we received some interesting submissions based on a supposed statistical approach to the likelihood of a contribution to the causation of a particular claimant’s mesothelioma having been made while he was employed by one or other of the defendants (if more than one) who happened to be before the court.  These arguments were not raised in the courts below except when final submissions on behalf of the claimant were made to Curtis J in Fairchild, and in the absence of a sufficiently firm foundation of factual and expert statistical evidence we do not consider that it is appropriate to draw any conclusions from them which favour the claimants’ case.
8.	Occupiers’ liability: The law.  (i)  Three different issues of law
109.	The three appeals of Babcock, Dyson and  Fairchild raise three different issues relating to the legal relationship between the occupiers of premises and workmen employed by independent contractors who are lawfully engaged in carrying out work at those premises.  In Babcock Mr Hussey, employed by Babcock, worked at the Battersea and Barking power stations of which the CEGB were the occupiers, between 1953 and 1955.  The CEGB’s liability, if any, falls to be determined by common law principles.  In Dyson, Mr Twohey, employed by Lindleys, worked at a number of maintained schools of which Leeds City Council were the occupiers, between 1958 and 1968, those being the years when Judge Bush held that that council, at any rate in their capacity as employers viz a viz their own labour force, knew or ought to have known the dangers posed by asbestos dust.  In Fairchild, Mr Fairchild, employed by G H Dovener & Son, worked at the Meanwood Baths, of which the same council were the occupiers, in 1962.  He also worked for B Slack & Sons at premises of which Waddingtons were the occupiers, between 1964 and 1968.  The liability of these occupiers, if any, to Mr Twohey and Mr Fairchild, falls to be determined by the Occupiers’ Liability Act 1957, alternatively by the common law.  Finally, for a brief period in about 1966-68 Mr Fairchild visited the Waddingtons premises after they had been converted into a factory, and for that period Waddingtons admit that they owed him duties pursuant to section 63(1) of the Factories Act 1961.
110.	It is therefore necessary in these appeals to consider the relevant provisions of the common law prior to the enactment of the Occcupiers’ Liability Act; the relevant provisions of that Act together with any concurrent liabilities at common law; and the provisions of section 63 of the Factories Act 1961.
(ii)  Section 63(1) of the Factories Act 1961
111.	It is convenient to start with the Factories Act 1961 because Waddingtons does not dispute its effect. It was a consolidation Act, and by section 63(1) it re-enacted section 47(1) of the Factories Act 1937, which was in these terms, so far as is relevant:
“In every factory in which, in connection with any process carried on, there is given off any dust or fume or other impurity of such a character and to such extent as to be likely to be injurious or offensive to the persons employed, or any substantial quantity of dust of any kind, all practicable measures shall be taken to protect the persons employed against inhalation of the dust or fume or other impurity and to prevent its accumulating in any workroom, …”
112.	Waddingtons admit that they did not take all practicable measures to protect Mr Fairchild from dust, and that they owed him a duty under this sub-section.  Their only defence is the causation defence which we have already considered.
(iii)  The common law liability of an occupier before 1957
113.	The common law made a distinction between the liability of an occupier for the dangerous condition of his premises and the liability of an occupier in relation to dangerous activities carried out on his premises.  In the cases this distinction was made by Denning LJ in Abbott v Dunster [1954] 1 WLR 58, 62 (see also Wheat v E Lacon & Co Ltd [1966] AC 552 per Lord Denning at p 580) and by Lord Gardiner LC in Commissioner for Railways v McDermott [1967] AC 169, 186-7.  It was also discussed by academic writers (see, in particular, an article by F H Newark at (1954) 17 MLR 102, 109-110 and P M North, Occupiers’ Liability (1971), pp 71-81).
114.	The distinction is sometimes made between “occupancy duties” and “activity duties”, and sometimes between duties relating to “the static condition of the premises” and “current operations”.  The latter is the language used by Denning LJ in Abbott v Dunster at p 62:
“In this case … it does not matter whether the plaintiff was an invitee or a licensee.  That distinction is only material in regard to the static condition of the premises.  It is concerned with dangers which have been present for some time in the physical structure of the premises.  It has no relevance in regard to current operations, that is, to things being done on the premises, to dangers which are brought about by the contemporaneous activities of the occupier or his servants or of anyone else.”
115.	In Commissioner for Railways v McDermott Lord Gardiner LC said at p 186:
“… The basic principle for a case such as this is that occupation of premises is a ground of liability and is not a ground of exemption from liability. It is a ground of liability because it gives some control over and knowledge of the state of the premises, and it is natural and right that the occupier should have some degree of responsibility for the safety of persons entering his premises with his permission.  In the language of the well-known passage in Lord Atkin’s speech in Donoghue v Stevenson there is a ‘proximity’ between the occupier and such persons, and they are his ‘neighbours’.  Thus arises a duty of care, but the measure of it is not defined by or derivable from Donoghue v Stevenson.  At common law the measure of that duty is a limited one …
But there is no exemption from any other duty of care which may arise from other elements in the situation creating an additional relationship between the two persons concerned.  Theoretically in such a situation there are two duties of care existing concurrently, neither displacing the other.  A plaintiff could successfully sue for breaches of either or both of the duties if the defendant had committed such breaches, although for practical purposes the plaintiff could be content with establishing the general duty and would not gain anything by adding the special and limited duty.”
116.	An occupier’s occupancy duties towards his invitees, including visiting workmen, were set out by Willes J in Indermauer v Dames (1866) LR 1 CP 274, 286:
“And, with respect to such a visitor at least, we consider it settled law, that he, using reasonable care on his part for his own safety, is entitled to expect that the occupier shall on his part use reasonable care to prevent damage from unusual danger, which he knows or ought to know; and that, where there is evidence of neglect, the questions whether such reasonable care has been taken, by notice, lighting, guarding, or otherwise, and whether there was contributory negligence in the sufferer, must be determined by a jury as matter of fact.”
117.	In London Graving Dock Co Ltd v Horton [1951] AC 737 the House of Lords explained that an unusual danger, or an unusual risk, in this context was one which was not normally found in carrying out the task which the invitee had in hand.  Lord Porter said at p 745 that he thought that the word “unusual” was used in an objective sense, although what was unusual would of course vary with the reasons for which the invitee entered the premises.  See also Lord Normand at p 752 and Lord Reid (agreeing on this point) at p 755.  If there was no unusual danger on the premises, no occupancy liability could arise (see pp 745, 752 and 776-7).
118.	That an occupier’s occupancy duties arise from unusual dangers in the static condition of his premises is clear from the helpful lists of what had been held, respectively, to be unusual and not unusual dangers in the 3rd Edition of Charlesworth on Negligence (1956) at pp 195-197.
119.	The emerging distinction between occupancy duties and activity duties can be seen in Glasgow Corporation v Muir [1943] AC 448, a case in which children were scalded when two members of a picnic party were engaged in carrying an urn of boiling tea through the defender’s shop.  Lord Thankerton made it clear at pp 462-3 that that case was not concerned with an unusual danger in the structural condition of the shop premises.  If it had been, the issue would have been whether the invitor knew or ought to have known that the invitees were being exposed to that unusual danger.  Instead, the question was whether in granting permission for the two men to carry the urn through the shop, the manageress of the shop did not use reasonable foresight to guard the children from unusual danger arising from the use of the premises.  In other words, the ordinary common law principles of the law of negligence were applied in deciding whether she was careless in the steps she took to guard the children from harm.  The House of Lords held that she was not.
120.	On this analysis, it is clear that the CEGB owed no occupancy duties (according to the Indermauer v Dames line of authority) in relation to the activities of Babcock and other contractors at their power stations if Mr Hussey’s only complaint related to the dust raised in the course of those activities.  It is therefore not necessary to say anything about the interesting submission we received about the non-delegable nature of an occupier’s occupancy duties, or indeed the interrelationship between passages in the speeches in the House of Lords in Thomson v Cremin [1956] 1 WLR 103, 110, Davie v New Merton Board Mills Ltd [1959] AC 604, 642-5 and 647-8 and Wheat v E Lacon & Co Ltd [1966] AC 552, 580.
121.	It follows that any duty the CEGB may have owed in these circumstances to a workman like Mr Hussey, who was employed by an independent contractor, could only have arisen from some other relationship recognised by the common law as giving rise to a duty of care and not from its liability as the occupier of the premises as defined in Indermauer v Dames and the cases which followed it.
(iv)  The Occupiers’ Liability Act 1957 and common law liabilities since 1957
122.	The Occupiers’ Liability Act 1957 provides, so far as is material, that:
“1(1)  The rules enacted by the two next following sections shall have effect, in place of the rules of the common law, to regulate the duty which an occupier of premises owes to his visitors in respect of dangers due to the state of the premises or to things done or omitted to be done on them.
  (2)  The rules so enacted shall regulate the nature of the duty imposed by law in consequence of a person’s occupation or control of premises and of any invitation or permission he gives (or is to be treated as giving) to another to enter or use the premises, but they shall not alter the rules of the common law as to the persons on whom a duty is so imposed or to whom it is owed; and accordingly for the purpose of the rules so enacted the persons who are to be treated as an occupier and as his visitors are the same (subject to subsection (4) of this section) as the persons who would at common law be treated as an occupier and as his invitees or licensees. …
2(1) An occupier of premises owes the same duty, the ‘common duty of care’, to all his visitors, except in so far as he is free to and does extend, restrict, modify or exclude his duty to a visitor or visitors by agreement or otherwise.
  (2)  The common duty of care is a duty to take such care as in all the circumstances of the case is reasonable to see that the visitor will be reasonably safe in using the premises for the purposes for which he is invited or permitted by the occupier to be there.
  ….
  (4)  In determining whether the occupier of premises has discharged the common duty of care to a visitor, regard is to be had to all the circumstances, so that (for example) –
a)	where damage is caused to a visitor by a danger of which he had been warned by the occupier, the warning is not to be treated without more as absolving the occupier from liability, unless in all the circumstances it was enough to enable the visitor to be reasonably safe; and
b)	where damage is caused to a visitor by a danger due to the faulty execution of any work of construction, maintenance or repair by an independent contractor employed by the occupier, the occupier is not to be treated without more as answerable for the danger if in all the circumstances he had acted reasonably in entrusting the work to an independent contractor and had taken such steps (if any) as he reasonably ought in order to satisfy himself that the contractor was competent and that the work had been properly done.”
123.	The meaning of some of these statutory provisions was considered by the House of Lords in Ferguson v Welsh [1987] 1 WLR 1553.  In that case a council had engaged Mr Spence to carry out demolition works on one of their sites.  Mr Spence was prohibited from sub-contracting without the council’s consent, but in breach of that provision he was said to have engaged the two Welsh brothers to do the work.  One of them employed Mr Ferguson to help them.  Mr Ferguson sustained serious injuries when part of the building collapsed.  The judge found that the system of demolition adopted by the Welsh brothers was highly dangerous.
124.	The judge held that the Welsh brothers were liable, but acquitted Mr Spence and the council of any liability.  The Court of Appeal admitted new evidence which tended to show that Mr Spence might indeed have sub-contracted the work to the Welsh brothers, and ordered a retrial as against him but not as against the council.  The House of Lords was concerned only with the question whether the claim against the council should also be tried again.  Lord Keith said at p 1559E that there was evidence capable of establishing that Mr Spence had ostensible authority from the council to invite the Welsh brothers and their employees onto the site, so that they were capable of being treated as the council’s visitors for the purposes of the 1957 Act.
125.	Lord Keith, with whom Lord Brandon, Lord Griffiths and Lord Oliver agreed, was content to dismiss the appeal by concentrating on section 2(4) of the Act.  Even supposing that Mr Ferguson was using the premises for the purposes of demolishing them, so that the common duty of care identified in section 2(2) was owed to him, he was satisfied that the council would have a watertight defence under section 2(4).  It had engaged Mr Spence, whom it had reasonable grounds for regarding as competent, and there was no evidence to support any inference that the council or its responsible officers knew or ought to have known that he was likely to contravene the prohibition on sub-contracting.
126.	Lord Keith did not devote much attention to section 2(2).  He thought (at p 1559H) that the council must be taken, if the new evidence was accepted, to have invited Mr Ferguson onto the premises for the purpose of demolishing the building.  He commented in passing that it was more difficult to hold that Mr Ferguson was, within the meaning of section 2(2), “using the premises for the purpose of demolishing the building” (emphasis added) before going on to address the section 2(4) issue.  
127.	Lord Goff, on the other hand, based his decision to dismiss the appeal entirely on his interpretation of section 2(2).  He said (at pp 1563D-1564A):
“I am content to assume, for the purposes of the present appeal, that there is evidence capable of establishing that Mr Spence did have the ostensible authority of the council to allow the Welsh brothers (and, through them, Mr Ferguson) onto the land,  Even so, in my judgment Mr Ferguson’s action against the council must fail because I cannot see how the council could be held liable to him, in particular under the Occupiers’ Liability Act 1957.
On the assumption that Mr Ferguson was the lawful visitor of the council on the land, the council owed to him the common duty of care, ie a duty ‘to take such care as in all the circumstances of the case is reasonable to see that the visitor will be reasonably safe in using the premises for the purposes for which he is invited or permitted by the occupier to be there’: see section 2(2) of the Act.  I have emphasised the words ‘in using the premises’ because it seems to me that the key to the problem in the present case lies in those words.  I can see no basis, even on the evidence now available, for holding that Mr Ferguson’s injury arose from any breach by the council of that duty.  There can, no doubt, be cases in which an independent contractor does work on premises which result in such premises becoming unsafe for a lawful visitor coming upon them, as when a brick falls from a building under repair onto the head of a postman delivering the mail.  In such circumstances the occupier may be held liable to the postman, though in considering whether he is in breach of the common duty of care there would have to be considered, inter alia, the circumstances specified in section 2(4)(b) of the Act.  But if I ask myself, in relation to the facts of the present case, whether it can be said that Mr Ferguson’s injury arose from a failure by the council to take reasonable care to see that persons in his position would be reasonably safe in using the premises for the relevant purposes, the answer must, I think, be no.  There is no question as, I see it, of Mr Ferguson’s injury arising from any such failure; for it arose not from his use of the premises but from the manner in which he carried out his work on the premises.  For this simple reason, I do not consider that the Occupiers’ Liability Act 1957 has anything to do with the present case.”
128.	Lord Goff went on to say (at p 1564A-D) that he did not subscribe to the opinion that the mere fact that an occupier might know or have reason to suspect that the contractor carrying out the work on his building might be using an unsafe system of work could of itself be enough to impose upon him a liability under the 1957 Act, or indeed at common law, to an employee of the contractor who was thereby injured, even if the effect of using that unsafe system was to render the premises unsafe and thereby to cause the injury to the employee.  He recognised that there might be special circumstances which might render another person liable to the injured man together with his employer, as when they were, for some reason, joint tortfeasors, but such a situation appeared to him to be quite different.
129.	While we must not assume that in using the language adopted in section 2(2) of the 1957 Act Parliament necessarily decided to adopt the emerging distinction between “occupancy liability” and “activity liability”, the selection of the phrase “care … to see that the visitor will be reasonably safe in using the premises for the [invited or permitted] purposes” is a fairly strong indication that Parliament intended the Act to be concerned with what used to be described as “occupancy liability”.  Section 1(1) refers to dangers due to the state of the premises or to things done or omitted to be done on them, and Lord Keith at p 1560F-G explained the need for the final words when he posited that a visitor might be struck by falling masonry which was only a danger because an obviously incompetent contractor had failed to secure it properly.
130.	We have had the benefit of much fuller argument than was available to the House of Lords in Ferguson v Welsh, and we can see nothing in the speeches of the other members of the House which casts any doubt on the correctness of Lord Goff’s interpretation of section 2(2).  Lord Oliver clearly tended to make the same distinction between occupancy liability and activity liability when he said, quite shortly, at p 1562E-F:
“It is possible to envisage circumstances in which an occupier of property engaging the services of an independent contractor to carry out work on his premises may, as a result of his state of knowledge and opportunities of supervision, render himself liable to an employee of the contractor who is injured as a result of the defective system of work adopted by the employer.  But I incline to think that his liability in such case would be rather that of joint tortfeasor than of an occupier.”
Lord Keith, too, was tending in the same direction at p 1560B in the sentence which starts “It would be going a very long way to hold …”
131.	In the recent case of Makepeace v Evans Brothers (Reading) (CAT 23rd May 2000) Mantell LJ said at paragraph 7 that the question whether the common law duty of care is subsumed in the common duty of care created by the 1957 Act or survived as an independent basis of claim in respect of activities carried out on premises was of no practical importance save possibly as a pleading point, and that it was unnecessary to attempt to resolve the question on that appeal.  The present appeals show how it may be essential sometimes to make this distinction.  The 1957 Act imposed the new statutory common duty of care on an occupier towards all his visitors to take appropriate care to see that they would be reasonably safe in using his premises, and it is not necessary in this context to go further than the provisions of the Act to see whether a duty of care exists or what is its scope.  The Act does not provide an answer, however, when a question arises whether an occupier, without more, is liable to a visitor for an injury he suffers as a result of an activity conducted by a third party on his premises.  For that purpose one has to go to the common law to see if a duty of care exists, and if so, what is its scope, or to some other statutory provision such as the (new repealed) section 63(1) of the Factories Act 1961.
132.	There is one other case which we should mention, if only because Eady J referred to it in his judgment in Babcock.  In Roles v Nathan [1963] 1 WLR 1117 the defendant was the owner and occupier of the Manchester Assembly Rooms.  Difficulties were experienced with the old coke heating boiler on the premises and during the course of the necessary works two sweeps, whose widows brought the proceedings, were engaged to clean the flues.  The sweeps were warned more than once by a boiler expert that the fumes from the boiler were dangerous, but they ignored his warning and were later found dead in the boiler room.
133.	The majority of the Court of Appeal (Lord Denning MR and Harman LJ) applied sub-sections 2(3) and 2(4) of the new Act to the facts of the case, and acquitted the occupier of liability. We do not consider that there is anything in the judgment of Lord Denning MR (at pp 1123-4) which casts any particularly useful light on the facts of the cases with which we are at present concerned.
9.	Occupiers’ liability: the judgments.  (i) Babcock
134.	Eady J was concerned with Babcock’s claim against National Grid for an indemnity or contribution in respect of the agreed damages of £80,000 which Babcock paid to Mr Hussey’s widow.  It was common ground that Mr Hussey’s exposure to asbestos dust and fibres arose during his period of employment with Babcock as a welder at the two power stations between September 1953 and December 1955.
135.	We have described the nature of Babcock’s involvement in the work at those power stations in paragraph 15 above.  There were, of course, a number of contractors or sub-contractors working at these enormous sites, but the judge said that it was not now known which firm was responsible for lagging at Battersea and Barking.  It was quite likely that they were employed by Babcock, but the judge was not in a position to make any findings about that.  Mr Hussey was a welder, but in the ordinary course of his work there he would have been exposed to asbestos dust and fibres which he would he bound to inhale.  His widow, who married him in 1972, said that her husband had told her that his job with Babcock was the best job he had ever had.  But even before he fell ill, he had told her: “The trouble with the job was that bloody asbestos.  I used to have to brush it off my moustache”.  He said they complained about it to the foreman, who told them that the dust was not lethal and that they were not to worry.  
136.	The judge mentioned in his judgment how one of the witnesses, Mr Stanley Dickson, who had worked for Babcock at Barking, had told him he remembered seeing asbestos dust falling from time to time like snow.  He described how the people working on the site would regularly have to clean it from their clothes and bodies at the end of the day.  In his witness statement Mr Dickson had explained how the Central Electricity Authority (which the CEGB was then called) was never involved in the control or the day to day management of the construction of the power station.  So far as he was aware, its only involvement at Barking was the operation of the security gate providing access to the site.  We admitted as fresh evidence on the hearing of the appeal what appeared likely to be the standard form of contract which would have been used to define the relationship between the CEGB (or CEA) and Babcock, but we did not find that this contract shed any light on the resolution of the issues we had to decide.
137.	The judge said that he was dealing with a situation where everyone with managerial responsibilities on the site would have known perfectly well that there was going to be a great deal of asbestos dust or fibre in the atmosphere and would have known at least of the risk of respiratory disease.  He was influenced by Glasgow Corporation v Muir (see para 119 above) and by the judgment of Lord Denning MR in Roles v Nathan [1963] 1 WLR 1117 (see para 132 above) to ask himself: could the CEGB reasonably expect the various specialist firms to take care of their staff so far as the risks associated with the lagging of power stations were concerned?  He answered this question in the affirmative.  He went on to say that if, contrary to this view, there had been a breach of duty on the part of the CEGB, he would have apportioned 100% liability to Babcock.  It had a clear non-delegable duty to Mr Hussey, and the responsibility for Mr Hussey’s misfortune overwhelmingly lay with Babcock, who had failed to warn its staff of the risks of asbestos or provide them with suitable protection, such as a respirator.  The extent of the CEGB’s management control was limited, and it understandably left the experts to progress matters in accordance with their experience and knowledge of the tasks in hand.
(ii)  Dyson
138.	We have described the nature of Mr Twohey’s work for Lindleys at the schools in the Leeds area in paragraph 17 above.  Judge Bush, sitting in the Leeds County Court, found that no precautions were taken against the asbestos dust and fibres generated in the work.  He set out in his judgment the effect of the evidence given by Mr Gerald Broadbent, who had been employed by the Leeds City Council (“Leeds”) as an assistant hearing engineer at the material time.  Mr Broadbent said that it was not until the mid-1970s that precautions were taken in handling asbestos on jobs like the one Mr Twohey did, but by that time most of the small sub-contracting firms had stopped doing work for the council.
139.	The judge conducted a review of the public warnings given from time to time during the last century about the risks of asbestos dust, and concluded that by the end of 1958 Leeds should have obtained the published material about asbestos and ensured that its responsible officers were familiar with its contents.  Leeds should have been aware by that time that damping and the provision of masks would reduce the risk considerably and they should have implemented those measures for their own employees.  He did not find, however, that Leeds was actually aware of this literature.  He contrasted their inaction from 1958 onwards with their action in issuing “a comprehensive and admirable body of instructions” after the introduction of the Asbestos Regulations in 1969.
140.	We interpret his finding as meaning that in their capacity as employers Leeds owed a relevant duty of care to their staff from 1958 onwards.  The law, after all, requires of an employer that he must take positive thought for the safety of his workers in the light of what he knows or ought to know (Stokes v Guest Keen and Nettlefold (Bolts and Nuts) Ltd [1968] 1 WLR 1776, 1783).  The judge went on to ask himself whether in consequence of his finding as to constructive knowledge Leeds owed any duty to Mr Twohey.
141.	He held that they did not.  He was influenced in this regard by Mr Broadbent’s evidence that Lindleys, who were engaged by Leeds General Infirmary and by two large private schools as well as by Leeds, were on a list of approved contractors who were expected to do their jobs skilfully and competently and to know their trade.  The judge quoted extensively from the speeches in the House of Lords in Ferguson v Welsh, and accepted that at the material time Leeds did not have actual knowledge that the system of work being employed by Lindleys was unsafe.  He expressed his conclusion in these terms:
“In my judgment, the circumstances of this case do not take it outside the principle enunciated in Ferguson v Welsh.  The defendants engaged contractors whom they had reasonable grounds for regarding as competent.  Both the defendants and Lindleys were aware of the presence of asbestos on the boilers and pipes and, in my judgment, it was not reasonable to expect the defendants to supervise Lindleys’ activities in order to ensure that they discharged their duty to their own employees.  It is right that Mr Broadbent regarded himself as having the power to instruct Lindleys’ employees as to the method of work they should adopt but, in my view, that cannot be equated with the assumption of a duty by the defendants so to instruct Lindleys or their employees.”
142.	The judge went on to take comfort from the fact that Eady J had reached a similar conclusion in the Babcock case.  Applying Eady J’s test he answered in the affirmative the question whether Leeds could reasonably expect Lindleys to take care of their staff so far as the risks associated with the stripping and lagging of heating boilers and pipes were concerned.
(iii)  Fairchild
143.	Curtis J dealt with the occupiers’ liability side of the Fairchild case quite briefly.  At the start of his judgment he mentioned the Factories Act claim against Waddingtons and said that otherwise the claims against both defendants were under the Occupiers Liability Act.  He overlooked the fact that he had also received submissions from the claimant founded on allegations of negligence at common law, and at the end of his judgment he overlooked the claim against Waddingtons as occupiers and concerned himself only with a claim against Leeds City Council (“Leeds”) under the 1957 Act.
144.	We have referred to Mr Fairchild’s exposure to asbestos dust at the Meanwood Baths and at the Waddingtons building in paragraphs 4, 6 and 7 above.  So far as his work for Leeds was concerned, the judge said that Mr Fairchild’s first employers were a family business owned by a Leeds city councillor.  They held a number of municipal contracts, and he was not prepared to find that they were other than a reputable firm.  He made the same finding in relation to the sub-contractors in other trades employed at the Meanwood Baths, including, in particular, those in charge of the de-lagging work.
145.	He said that Leeds was entitled to engage a multiplicity of trades and to entrust them with work within their professional competence. In those circumstances he said that common sense told him that the primary duty for ensuring Mr Fairchild’s safety from asbestos dust lay with his employers by keeping him away from it, or by providing breathing equipment or taking reasonable steps to see that the employers of the “de-laggers” minimised so far as was reasonably practicable the proliferation of dust near the places where their staff worked.  He said that this was a perfectly normal site renovation.  There was nothing esoteric or special about it.
146.	Like Judge Bush in Dyson, Curtis J took comfort from the fact that Eady J had arrived at a similar conclusion in Babcock.  He was of the view that Leeds could reasonably expect the various specialist firms to take care of their staff so far as risks from asbestos were concerned.  He adopted Judge Bush’s finding that Leeds did not actually know of the asbestos risk in 1962, even though they ought to have done.
147.	There was one feature of the evidence which Curtis J did not mention in his judgment.  The council called no evidence, but they had disclosed on discovery a witness statement made by a Mr Loades in other litigation, and Mr Fairchild’s advisers had adopted this statement as part of their case.  This statement was mostly concerned with other matters.  Mr Loades had, however, been a clerk of works in Leeds’s public works department between 1951 and 1962, and he described how when he was working in that capacity in the North Leeds area, Leeds employed contractors on a time and materials schedule basis.  The order in respect of particular work was sent to the contractor concerned, who would supply Leeds’s local office with time sheets.  The work was then supervised by the clerk of works or works department foreman.  Because Mr Loades had not been asked about the Meanwood Baths works, there was no evidence which tended to show whether Leeds employed contractors on this basis on a job as big as that, or whether they engaged main contractors who engaged firms like G H Dovener & Son on a sub-contract basis.
148.	So far as the work at Waddingtons was concerned, the judge received evidence from Mr Peter Brock, who worked for Mr Fairchild’s then employers as a painter.  While that building was being gutted and renovated, he would drive Mr Fairchild and other colleagues to the site every day.  He used to go into the building every now and then, and he said that the conditions were terrible.  There was strip lagging in bags and on the floor and dust everywhere.  Neither his employers nor Waddingtons provided any fans.  Mr Fairchild, in his statement, gave similar evidence.  He said that they used to do what they could to increase the ventilation by opening the doors and windows, but he remembered the conditions being fairly unpleasant.
10.	Occupiers’ Liability:  Conclusions
149.	It is unnecessary to discuss in detail the argument we received on these three appeals.  Much of it is subsumed in the analysis of the law in Section 8 of this judgment.  For the reasons set out there we do not consider that we are concerned here with an occupancy liability, as the law stood prior to 1957.  The Babcock case is not concerned with Mr Hussey suffering injury from something in the static condition of those two power stations which posed an unusual danger.  Nor do we consider that the Occupiers’ Liability Act imposed any statutory duty of care which is relevant on these appeals, so far as Waddingtons and the Leeds City Council were concerned.  The statutory duty of care created by that Act imposed a duty on those occupiers to see that Mr Fairchild was reasonably safe in using the premises for the purposes for which he entered them, and he encountered no dangers in his use of the premises, as he would have done if he had fallen through an unguarded hole in the floor.  It was what was going on in those premises which caused him harm.
150.	It follows that these defendants’ liability, if any, must arise from the operation of the common law.  So far as Babcock are concerned, we cannot fault Eady J’s approach.  The CEGB hired highly reputable contractors, and we can see no reason why in the circumstances of that case the law should impose any liability on them, in their capacity as (virtually) absentee occupiers, when it was Babcock’s duty to look after the health and safety of their employees. To impose such a liability would in effect require an occupier to owe an employer’s duty of care to somebody else’s employees; indeed, it could be argued that it would impose on an occupier an even more rigorous duty of care in that it would require him to ensure that the employer was carrying out his own duty of care. We can see no principled reason for imposing such a duty. In any event we can also see no grounds for disturbing the judge’s decision on apportionment, even if both he and we are wrong on the question of primary liability.
151.	So far as the other two appeals are concerned, there is no finding that any of the occupiers before the court knew of the risks which Mr Twohey and Mr Fairchild were running.  We were told that it was not until the end of the 1960s that statutory regulations were introduced which brought home the nature of the risk not just in a factory setting but in the context of mundane jobs like that of stripping asbestos lagging off boilers and pipes in the course of the daily work of a plumber or heating engineer.  Ignorance of risks cannot excuse an employer, because it is an employer’s duty to find out about well-known risks which may imperil his workforce, but we were not shown any authority which suggested that such a duty rested on a mere occupier who had engaged competent contractors.
152.	In Ferguson v Welsh (at p 1561B) Lord Keith, who approached the case on the basis that the 1957 Act could be applicable, distinguished the performance of work by competent contractors from “the unsafe working methods of cowboy operators”.  Lord Goff at p 1564C recognised that there might be special circumstances where the law of negligence might impose a duty on someone other than an employer.  But given the judges’ findings that Lindleys, G H Dovener & Son, and B Slack & Sons could reasonably be regarded as competent employers well capable of looking after their employees’ safety, we do not see any scope for the common law to impose a duty of care on the occupiers of the premises where those employees went out to do their work, when the danger they encountered arose not from the static state of the premises but from the way in which they did their work, and from the risks to which they were exposed by others who were working alongside them, either as co-employees or as employees of other competent independent contractors.
153.	It was argued that the defendants should not have regarded the employers as competent, given that they were exposing their men to risks from asbestos dust on a daily basis.  This argument is intelligible if there was a finding that the occupiers knew of the risk, whether or not the men’s employers also knew of it.  Given that they did not know of the risk, there is no basis for creating a duty by that route.  There is nothing in the recent decision of this court in Cherry Tree Machine Co Ltd v Dawson [2001] EWCA Civ 101, PIQR P265 which casts any light on the duty of occupiers, as opposed to the duty of employers, at the time with which these appeals are concerned.
154.	At one time we were concerned whether Leeds was in a different position in the Fairchild case, because there was evidence that on many jobs the council engaged contractors directly. It might therefore be argued that the risks that Mr Fairchild ran arose out of the fact that Leeds so arranged the individual contracts that lagging and de-lagging work was being carried on all round him as he carried on his duties as a joiner. We encountered the difficulty, however, that the claimant had not established on the balance of probabilities what arrangements had been made for the works at the Meanwood Baths. In this context we do not consider that Mr Loades’s evidence, prepared for another purpose, is sufficient to establish that Leeds would probably have adopted this piecemeal approach for works as big as these.  Since the claimant cannot in any event prove causation, it is not necessary to take this matter any further.
155.	For these reasons, we consider that Eady J, Judge Bush and Curtis J were all correct to hold that no liability attached to the CEGB, Leeds or Waddingtons in their capacity as mere occupiers of the premises in which Mr Hussey, Mr Twohey and Mr Fairchild were exposed to asbestos dust.
11.	Pendleton: Provisional Damages
156.	We have explained (see para 15 above) how in Pendleton the three defendants who were before the court consented to judgment against them for an agreed sum in respect of the injury relating to bilateral calcified pleural plaques, and how they also agreed to submit to an order for provisional damages to cover the chance that Mr Pendleton might at some time in the future contract asbestosis or diffuse pleural thickening as a consequence of his exposure to asbestos dust.  They resisted, however, the extension of that order to cover the risk of his contracting mesothelioma or lung carcinoma from the same cause.  They argued that if Fairchild was rightly decided, Mr Pendleton would never establish in law a cause of action or liability in respect of either of those diseases because he would never be able to establish which of the defendants exposed him to the putative fibre or fibres that caused the onset of the condition.
157.	The resolution of this dispute turns on the proper interpretation of section 51(1) of the County Courts Act 1984, which is in the same terms as section 32A(1) of the Supreme Court Act 1981:
“51(1)	This section applies to an action for damages for personal injuries in which there is proved or admitted to be a chance that at some definite or indefinite time in the future the injured person will, as a result of the act or omission which gave rise to the cause of action, develop some serious disease or suffer some serious deterioration in his physical or mental condition.”  
The procedure is now governed by CPR Part 41, which provides by CPR 41.2(1)(b) that the court may make an order for an award of provisional damages if it is satisfied that one or other of these statutory provisions applies.
158.	This statutory scheme was considered by this court in Hurditch v Sheffield Health Authority [1989] 1 QB 562.  In that case Mr Hurditch, who had been exposed to asbestos during successive periods of employment with different employers, included in his claim against his current employers a claim for provisional damages.  The defendants offered him the sum of £2,500 in respect of a “provisional figure for damages”.  He then issued a summons applying for leave to enter judgment in the terms that the defendants paid him this sum on the assumption that he would not as a result of their act or omission develop either bronchial carcinoma or mesothelioma or suffer deterioration in his physical condition due to asbestos-induced disease.
159.	The master held that there had been an offer to submit to an award pursuant to RSC O37 R9(3), that Mr Hurditch was entitled to an award in the sum agreed, and that the summons should be transferred to a judge for trial of the outstanding medical issues.  A judge in chambers allowed the defendants’ appeal and dismissed the summons, holding that there was no sufficient agreement between the parties to form the basis of an award of provisional damages.  This court then allowed Mr Hurditch’s appeal, but it did not reinstate the master’s order for a trial of the outstanding medical issues.
160.	Purchas LJ explained at pp 580G-581B that there was so little area of dispute between the doctors that the medical reports would almost certainly have been agreed, but even if they were not then it was perfectly open to file medical reports from each side so as to form the basis for further consideration.  (See now CPR 41 PD para 3.2(4)).  On such an occasion the whole question of causation of the new disease or serious deterioration would be open to argument both as to attributability as between one or other of the periods of exposure and also as to the carcinogenic dangers resulting from Mr Hurditch’s smoking habits.  Although he understood counsel’s submission that the resolution of such issues would be more difficult if proper investigation were not undertaken at that early stage, he was not impressed that this could be a reason for not making an award of provisional damages.
161.	He said (at p 581A-D) that he could see a difficulty arising in another case where there was a serious dispute as to the identification of the new diseases which might in the future be attributed to the wrong which gave rise to the judgment in the first place.  On an appropriate occasion he would have been minded to agree that there was jurisdiction to order the trial of a limited area of dispute as a separate issue, but this course was unnecessary in the present case.
162.	It is noteworthy that the rulemakers have recast the language of CPR 41.2 (when compared with CCR O22 R8 and RSC O37 R8).  The new rule omits the words “on such terms as it thinks just and subject to the provisions of this rule” in sub-rule 1.  CPR 41.2(2) is then cast in fairly prescriptive terms:
“(2)	An order for an award of provisional damages –
(a)	must specify the disease or type or deterioration in respect of which an application may be made at a future date;
(b)	must specify the period within which such an application may be made; and
(c)	may be made in respect of more than one disease or type of deterioration and may, in respect of each disease or type of deterioration, specify a different period within which a subsequent application may be made.”
163.	It follows that the court’s task is to decide whether there is a chance (proved or admitted) that at some definite or indefinite time in the future the claimant will as a result of [the exposure to asbestos while employed by the defendants] develop the identified disease or suffer the identified deterioration.
164.	Judge Tetlow, sitting in the Manchester County Court, said that it was apparent from a report by Dr Rudd that there was a chance that as a result of the acts or omissions of each of the defendants which gave rise to Mr Pendleton’s cause of action against them he would at some time in the future develop mesothelioma simply because one or more of those fibres triggered the malignancy.  He considered that if the mesothelioma (or lung cancer) was contracted in the future, then would be the time to argue which, if any, of the defendants was liable as a matter of legal causation, and that would be decided on the basis of the evidence available then to either party and upon the law as then established.
165.	Mr Taylor, who appeared for the three appellant companies, said that if (as we have now held) Fairchild was correctly decided, the development of an indivisible asbestos-related illness would not give rise to a claim for damages in a case where there has been admitted multiple exposure, because a claimant like Mr Pendleton will be unable to prove causation.  It could not have been intended that the provisions of this statutory scheme were intended to hibernate a putative cause of action in the hope or expectation that at some future date (should the conditions become manifest) medical science might have advanced, or that different principles of law might have been introduced which would enable damages to be recovered then although they could not be recovered if the disease had manifested itself now.  He said that it was unreasonable in such circumstances to require the court to make provisional awards and to retain the files, or to oblige defendants’ insurers to keep cases open, and to maintain reserves.
166.	In our judgment the judge was right for the reasons he gave.  There is indeed a chance that Mr Pendleton will at some future date develop mesothelioma or lung cancer as a result of his exposure to asbestos dust when employed by these defendants.  Whether he can prove that the negligence of one (or more or all) of the defendants caused these diseases, if sadly they ever appear, must depend on the state of medical science at that time, considered in the light of the law’s requirements as to causation.  This conclusion follows naturally from the language of section 51(1), and we would dismiss this appeal.
12.	The result of these appeals
167.	It follows that the appeal of the defendants in the Matthews case is allowed.  The other five appeals are all dismissed.