The research, in which the journalist Ed Moloney was involved, comprised interviews with paramilitary figures who were assured the material would remain unpublished until they died.

But public comments by the disillusioned IRA member Dolours Price alerted the Historical Enquiries Team (HET) - the PSNI unit headed by Dave Cox which is trawling through all Troubles-related deaths - to the evidence she had given to the archive on the murder in 1972, of Jean McConville, a widowed and impoverished mother of 10 living in the Divis Flats in west Belfast.

The IRA claimed Mrs McConville had been informing - an assertion which could have been coloured by her Protestant background and which is denied by her children. Her remains were discovered on a beach in Co Louth in 2003.

Price claimed that Gerry Adams, now the avuncular president of Sinn Fein, but then second-in-command of the IRA in Belfast, had ordered that Mrs McConville be murdered.

Moloney had already reported the claim in his 2002 book on the IRA, in which he said Adams had been responsible for establishing an IRA unit, called 'the unknowns', which 'disappeared' 14 individuals the organisation deemed worthy of a death-sentence.

Adams reacted vehemently when the book was published, threatening legal action, but none was pursued. He claims never to have been in the IRA, but he and Martin McGuinness were secretly flown by the British Government to London in 1972 to be part of an IRA delegation to talk to then-Northern Ireland secretary William Whitelaw.

The HET is going through each death since the Troubles began in chronological order. It will eventually get to 1986 and the IRA killing of the alleged informer Frank Hegarty in Derry, to 1987 and the Remembrance Day bomb in Enniskillen and to 1990 and the death of the so-called 'human bomb' Patsy Gillespie and five soldiers at a checkpoint at Coshquin in Co Londonderry.

The name which links these three cases is McGuinness. Now deputy First Minister at Stormont, and having formed half of the 'Chuckle Brothers' with Ian Paisley, he claims to have left the IRA in 1974.

In 1990 as the editor of Fortnight magazine, I interviewed him in his office in Derry for an article on the thinking of the IRA in the aftermath of its assassination of the high-profile Conservative Right-winger Ian Gow.

The Irish Times journalist Peter Murtagh recently rehearsed the claim by Frank Hegarty's family that he had been personally reassured by McGuinness that he was safe to return from exile to Derry - only to be murdered by the IRA when he did so. Murtagh reported too, the menacing reaction of McGuinness and his coterie.

In his 2002 book, Moloney revealed that McGuinness was 'northern commander' of the IRA when the northern command authorised the Enniskillen bombing. This was confirmed by BBC journalist Peter Taylor in a 2008 programme.

According to Moloney, McGuinness played a similar role in the sanctioning of the 'human bomb' tactic, first deployed when Gillespie was forced to drive his van to the Coshquin checkpoint, where the bomb the IRA had put in the vehicle was detonated remotely. The revulsion caused by the sheer inhumanity of the tactic led to its rapid abandonment.

Gordon Wilson, who held the hand of his dying daughter, Marie, at Enniskillen, went on to become a reconciliation campaigner. So has Kathleen Gillespie, Patsy's widow.

All the serious research on Northern Ireland showed that the principal problem was sectarian division, sustained by official neglect in London, shading into paramilitary violence at the margin. Yet the superficial thinking underlying the 'peace process' of the 1990s was that the problem was the 'men of violence', reduced to the IRA.

The implication was that the Government had to negotiate with the IRA, having failed to suppress it and so there was to be official silence on paramilitary crimes.

It might have been hoped in London there could be silence, too, on state violence, but public pressure from the families of those murdered prevented that Bloody Sunday.

To comply with today's international norms, those guilty of war crimes, from whatever quarter, should have faced prosecution, not been given immunity. And the evidence on Adams and McGuinness, as it emerges, will be explosive.

At the same time, it will be hard for the prime minister to keep resisting an inquiry into the killing of Pat Finucane, murdered by the UDA, but with the collusion of the shadowy Force Research Unit (FRU) within the Army.

If the weak link in the 1974 power-sharing experiment was the ill-conceived Council of Ireland, failure to deal with the past is the Achilles' Heel of the current arrangement at Stormont.

The clock is ticking.