There are nearly one million documents on microfiche sitting in the office of the Manchester Metropolitan University Business School academic Geoffrey Tweedale. They expose a scandal that ranks among the biggest and costliest of our age: how the Lancashire manufacturing giant Turner & Newall (T&N), once the world's largest asbestos conglomerate, exposed millions to a lethal carcinogen in full knowledge of its dangers, using PR firms and politicians to hide a truth that it had secretly admitted to in 1961, namely that "the only really safe number of asbestos fibres in the works environment is nil".

Hidden in this massive archive are documents, revealed here for the first time, which tell the story of corporate recklessness that has led to the deaths of thousands of men and women in Britain who were once exposed to asbestos.

People living in the Spodden Valley area of Rochdale in the 1950s used to joke that they would get frost all year round. The local wood was nicknamed "the snow trees" and even the blackberries picked in late summer were covered with a fine white powder. But the "frost" was no joke - it was asbestos blown from extractor fans at the Turner & Newall factory in the heart of the valley.

Derek Philips never worked there, but for 19 years lived just yards from the site. He played bass in a band with T&N workers and recalls the factory as "the centre of the community". The guitars hang on the walls of his current home, a static caravan in the Pennine foothills where he waits to die of one of the asbestos-related diseases - meso thelioma, which appears decades after exposure to asbestos and which is killing more than 2,000 people every year in the UK.

His plight has been all too common in Rochdale. In the 1980s the New Statesman reported that on some roads near the factory every second household had lost a family member to asbestos diseases.

"I was diagnosed in October [2007]," says Philips. "A month later they drained three litres of fluid from my lungs. I couldn't even stand up properly. I've just no chance, have I? I didn't know about the risks."

In the coming months, how he was exposed to asbestos and who he was working for at that time will become vital issues as lawyers fight to win compensation for Derek.

The latest gambit of some insurers is to claim that their liabilities extend only to victims whose disease manifests (is triggered) when they are actually at work, not when they were negligently exposed, which can occur decades earlier. The union Unite is backing one of six test cases that have been presented on behalf of victims to Mr Justice Burton, who will rule in the high court this autumn. If he finds for the insurers, thousands of mesothelioma victims could find themselves without compensation for their suffering.

This long-running war between victims and insurers has an unlikely new player: Warren Buffett, the richest man in the world, who will watch the results of the "trigger issue" case with interest. Next year, National Indemnity Company, a division of the billionaire's Berkshire Hathaway, will take control of an office in the City of London that is unable to respond to telephone inquiries and has only one full-time employee. This skeleton of a business is called Equitas. It was worth $8.7bn in cash and securities when Buffett took it over in 2006. It had been created a decade earlier by Lloyd's of London to solve a multibillion-dollar crisis in insurance: the overextended liabilities of Lloyd's Names.

Who is liable?

By the 1980s, the burden of asbestos-related insurance claims underwritten by Lloyd's Names had become so great that the Names were threatened with bankruptcy. Equitas was established to manage the liabilities. Nearly half its reserves are dedicated to asbestos reinsurance claims predominantly from the United States. Some experts considered even Equitas's billions insufficient to cover the insurers. Buffett's deal augments the fund by a further $7bn to cover any shortfall and the Names will heave a collective sigh of relief when the transaction is approved formally by the high court next year.

So, what is in it for Buffett? When the Financial Times first interviewed him about the proposed deal in 2006, he admitted: "It will be long after I am dead before we know the final answers on how it all works out." Meanwhile, however, he will gain access to some of the most capable reinsurance analysts in the world.

Geoffrey Tweedale, author of Magic Mineral to Killer Dust, comments: "The deal will only be profitable if Berkshire Hathaway can limit their liabilities." In other words, Buffett would have to limit payments to the insurers that compensate victims. Alistair Darling's "bonfire of red tape" announced in the last Budget will help.

In July, the Treasury amended the Employers' Liability Regulations to revoke the requirement for businesses to keep insurance records for 40 years. But, in asbestos-related cases, decades can pass between exposure and the development of the disease. Without records, victims may be unable to establish who is liable. Tony Whitston, who runs the Asbestos Victims Support Groups Forum UK, says: "It's a body blow to our groups who have to pick up the pieces when victims are unable to obtain justice."

The people of Rochdale have long experience of that.

Samuel Turner was a pioneer, spinning fireproof and corrosion-resistant textiles from Canadian asbestos on secondhand cotton machinery in the 1870s. From meagre beginnings, T&N grew to be the biggest asbestos conglomerate in the world, as well as a popular local factory.

Brian Penty worked at the site from 1963 until 1996: "There was a bowling green and Christmas parties for the kids," he explains. "It was a family thing. People never really took on board what was being said about asbestos."

Beneath the rosy tale of northern endeavour lurked a darker story. As early as 1898, government factory inspectors were warning that asbestos "easily demonstrated danger to the health of the workers". The T&N files first refer to asbestos cancer in Rochdale in the 1930s.

By 1947, the national factory inspector's report emphasised the incidence of lung cancer among asbestos workers but, astonishingly, no detailed research was undertaken by the government. Only in 1955 did Richard Doll, then a junior academic (and later famous for establishing the connection between tobacco-smoking and cancer), complete an epidemiological study in Rochdale which established the link between asbestos and cancer. He had been approached by T&N but the company initially refused to allow him to publish the findings. Later T&N persuaded its own scientist, Dr John Knox, to draft a paper discrediting Doll's work. Knox encouraged academic scepticism about asbestos diseases but clearly knew there was a problem. He regularly X-rayed employees and when the results showed them developing signs of disease moved them to less dusty jobs. They were not told why.

The signed witness statement of a worker who later died states: "They did not say in 1974 that I had asbestosis but I expect there was something on my X-ray which made them think it was time I came out."

And Brian Penty remembers a so-called "blood pressure survey" in 1982: "They actually drew blood. A couple of years later I was at my GP's surgery - he'd been sent the results. Apparently they were testing for asbestos in my bloodstream."

In public, T&N strove to be portrayed as a responsible employer. In 1944, a manager of the plant wrote to factory inspectors: "In a number of cases we make ex-gratia payments in addition to the statutory compensation. Where an employee has no standing for some technicality we pay compensation, as it appears desirable to deal with the problem on broad lines, and not to rely on some legal point in our favour."

Yet, when the first official asbestosis victim, Nellie Kershaw, died in 1924, the firm wrangled about paying compensation to her bereaved family. Finally they decided not even to contribute towards funeral expenses since, as one company manager warned, it "would create a precedent and admit responsibility". She was buried in an unmarked grave.

The T&N archives are full of death certificates of former employees, placed with internal correspondence never disclosed to grieving families. The official cause of death attributed to Edna Penham, a 64-year-old asbestos stripper at T&N, for example, was peritonitis. The company's personnel manager noted that his records showed she was "40 per cent disabled due to asbestosis", though there was no reference to this on her death certificate. It appears the coroner did not know. There was no inquest.

Keeping quiet

Eventually T&N employed the insurance giant Commercial Union to administer a fund for diseased employees. Geoffrey Tweedale found examples of former employees being placed under surveillance by the firm - desperate not to be held liable. Company policy appeared to be to mislead coroners' inquests, pay compensation only if forced and avoid payouts that might create precedents.

In 1964, T&N solicitors warned the directors: "We have, over the years, been able to talk our way out of claims but we have always recognised that at some stage solicitors of experience . . . would, with the advance in medical knowledge and the development of the law . . . recognise there is no real defence to these claims and take us to trial."

The company found government representatives only too pliant. One medical adviser is recorded as advising T&N to keep quiet about the cancer dangers of their product. In correspondence between two directors of the plant, the opinion of Professor Archie Cochrane, director of epidemiology at the Medical Research Council, was noted: "In tackling a problem of this nature [mesothelioma] one should either be completely frank with everyone or maintain complete secrecy - it is the latter that he feels is best at the moment."

In 1968, T&N circulated a confidential five-point plan entitled "Putting the Case for Asbestos". Drafted by the international PR firm Hill & Knowlton and designed to enable staff to field questions about asbestos cancer, it began, in capital letters: "Never be the first to raise the health question."

When government departments did raise questions about the safety of asbestos, the Board of Trade intervened, arguing that any suggestion that asbestos presented a danger would damage British jobs. So, the sale of asbestos products continued to grow in the UK throughout the 1960s and 1970s.

T&N also relied on the assistance of Cyril Smith, the larger-than-life Rochdale MP and parliamentary pioneer of the Saturday-night television chat-show sofa. During the summer recess of 1981, Smith wrote to Sydney Marks, the head of personnel, informing him that the House would debate EEC regulations on asbestos in the next parliamentary session.

The letter asks simply: "Could you please, within the next eight weeks, let me have the speech you would like to make (were you able to!), in that debate?"

T&N's draft is almost identical to the speech delivered by the Rochdale MP, stressing the need for less regulation and arguing that substitutes for asbestos should be approached "with caution". "The public at large are not at risk," said Smith. "It is necessary to say that time and time again."

Writing in the local paper, he claimed to have "worked very hard on the speech and have spent hours, both in reading and in being at the works, trying to master the facts about safety in asbestos".

A year later he declared 1,300 shares in the company. Six months after that J B Heron, the chairman of T&N, wrote to Smith again, thanking him for his assistance with the Commons select committee meetings which followed Alice, a Fight for Life, the Yorkshire Television documentary that highlighted the plight of T&N employees.

When last month the New Statesman approached Smith for a comment, he said: "If you've got the documents, it is all true."

Some may receive nothing

By 1999, the game was up for T&N when the European Union banned the import and production of asbestos throughout the EU. But with the factory's demise came the greatest in justice of all. In the UK, neither T&N nor its insurers faced substantial product liability claims or decontamination costs. Instead, the company was purchased by Federal-Mogul, a US company which later declared Chapter 11 bankruptcy - a status that ring-fenced its compensation liabilities.

With the company protected from its creditors, a UK-based T&N asbestos compensation scheme of just £100m was established by Federal-Mogul's UK administrators.

Those who, like Derek Philips, may have been victims of environmental exposure at T&N's factories may end up receiving little or nothing.

"The hardest thing," says David Cass, a solicitor specialising in compensation for mesothelioma victims, "is having to tell people who walk into my office, 'I won't get you an apology.'"

Who is left to provide one? T&N is now a shell. The civil servants and politicians who failed to regulate the industry are no longer in post; the insurers who took on the liabilities are long retired. They cannot account for their decisions now. But we will live, and many will die, with the consequences.

Asbestos: the killer facts

1

asbestos is the single greatest cause of work-related death in the UK

4,000

number of asbestos-related deaths in the UK in 2005

79

number of teachers who died from mesothelioma between 1991 and 2000

13,000

schools in Britain may have been built using asbestos materials

60

number of years after exposure to fibres it may take for an asbestos-related disease to manifest itself

25%

of victims of mesothelioma work in the building or maintenance industry

2.2 million

tonnes of asbestos were mined worldwide in 2005

Research: Adam Lewitt