WHILE the origin of the alleged transcript of a conversation between British Secret Intelligence Services agent "J118" and his handler remains mysterious, security sources in the North yesterday indicated that it may not be the only damaging piece of material due to come into circulation in the coming months.

There were always tensions between and within the security services, the RUC and British army in the North over the recruitment and handling of high-level IRA at a time when the IRA was still murdering police and soldiers. Many suffered from high stress levels and nurtured suspicions that highly dubious activities were being allowed for the sake of protecting informants and while attempting to control the course of the Troubles towards a final IRA defeat.

Since the ending of the Troubles these tensions have evolved into bitterness and anger among former members of the intelligence community who now wish to reveal the fact that deaths were allowed to occur to protect the identity of important informers. Senior security sources here and in the North believe that the claims made in the media last week that Martin McGuinness was a spy for the British have more to do with the historical residue of the intelligence "dirty" war in the North than with political point scoring, as Sinn Fein claimed last week.

"Martin Ingram", the former British army intelligence officer who said last week he believes the McGuinness/J118 document to be genuine, has a strong record on exposing the activities of Special Branch, British army intelligence and the IRA's own internal security department. He outed Freddie Scappaticci, former head of IRA internal security (of the "Nutting Squad" as it was known) as a British army agent. He also revealed the extent to which the members of the loyalist Ulster Defence Association unit that shot dead solicitor Pat Finucane were working for both the RUC Special Branch and British army intelligence.

Ingram is part of a small community of ex-intelligence officers who served in the North and who now occasionally release details of the people they recruited and what they did during some of the bloodiest years of the Troubles. Some have written books and some anonymously post information on websites. Many of these police and military intelligence officers suffered breakdowns after the Troubles ended as a result of the pressure they had been placed under. The decision by some to begin to talk about what they did and knew is - according to other former senior police - a kind of"therapy".

These former intelligence-gatherers on both sides of the border - who risked their lives to infiltrate and frustrate the IRA and loyalists - are said to be constantly reminded of what they did when they see former terrorists appearing in the media treated as proponents of the "peace process". "They see people parading on TV. They know what they did," one ex-police officer in the North said.

Some of the greatest successes scored by the RUC Special Branch, British army intelligence and the British Secret Intelligence Services took place in Martin McGuinness's backyard. By the mid-Eighties the Derry IRA was thoroughly infiltrated and undermined by police and military intelligence. Derry was once one of the most dangerous place in the North for police and soldiers. However, in the decade from 1984 to the IRA ceasefire in 1994 only 15 members of the security forces were killed in the city compared with just over 400 in the other parts of the North.

It is now known that the RUC and British military had recruited agents at a very high level in the IRA in Derry. McGuinness's second-in-command in Derry city was one of the most senior IRA figures ever recruited by the RUC Special Branch. He was able to direct them to arms dumps and to tip them off about imminent attacks, saving dozens if not hundreds of lives.

This role of this agent - his name is known to the Sunday Independent and he fled into British protection 13 years ago - has remained largely unknown outside Derry. However, it is now known that during his time working for the RUC he managed to walk a very thin line between maintaining the trust of McGuinness and other IRA leaders and working as a very successful agent for his police handlers. The roles at times conflicted and on a number of occasions his handlers were unable to prevent attacks going ahead which cost a number of lives and caused millions of pounds' worth of damage.

One such attack was in March 1989 when two soldiers delivering food to the army border checkpoint at Coshquinn were killed in a massive landmine explosion. The bomb was the prototype of the new type of massive, Semtex-boosted bomb which went on to kill dozens of people and cause billions of pounds' worth of property damage in Britain and Northern Ireland.

This agent's career in Derry came to an end when, during a binge in Donegal, he robbed an off-licence and was apprehended by local gardai. He 'Some of the greatest successes scored by British intelligence took place in Martin McGuinness's backyard'

was "turned" by a clever detective in Letterkenny and went on to provide invaluable information on the IRA in Donegal leading to real arms seizures, including the interception of a second "human bomb" attack aimed at the border crossing checkpoint outside Strabane. The man was held in Limerick Prison for over a year before being flown out to Britain and a new life. He has never resurfaced, and gardai say his life would probably still be indanger if he ever reappeared in Ireland.

What remains unclear is how the Derry IRA, which was so heavily infiltrated, managed to pull off the stunning human bomb attack on Coshquinn checkpoint on October 10, 1991. The operation is believed to have been the brainchild of the IRA's head of intelligence, who lived in north Donegal at the time, and directed by the then director of operations in "northern command", a Belfast man. The IRA had, on many occasions before, forced people to drive car and van bombs to security force or commercial targets. Families were held hostage and the head of the household told to drive the bomb to the target or have his family murdered. In all previous cases, however, the driver had to be given adequate time to escape or he would simply abandon the vehicle.

In the Coshquinn attack the IRA struck on a new idea - which has since been taken up by insurgents in Iraq. The driver, catering worker Patsy Gillespie, was put in the driver seat and beside him was a clock with wires attached. He was told he had 40 minutes to drive the van to the checkpoint or his family would be murdered.

What Gillespie did not know was that the bomb was wired to the switch in the door frame which set off the vanity light in the cab. When he stopped at the checkpoint and opened the door to alert the soldiers, he and five soldiers were killed instantly. It was one of the IRA's most awful and devastating attacks. The reality of what happened was only uncovered when the Donegal gardai intercepted a similarly primed lorry bomb the following year.

The thrust of the alleged "J118" transcript is that Martin McGuinness informed a British intelligence officer beforehand that the human bomb attack was to take place; and that the handler was keen for this to proceed as it was believed the adverse public reaction would increase pressure on the IRA to end its overall campaign. Indeed there was very strong reaction from the Catholic church, nationally and internationally, in the aftermath of the attack.

However, McGuinness is emphatic that the document is a fake and says he is "one million per cent" sure that no documents or evidence exist to link him to any such plot.

Senior Garda sources were as surprised as anyone last week when the story appeared in the Sunday World. In fact, the same allegation had been made as early as last January by "Martin Ingram" in an interview on the radical New York radio programme Radio Free Eireann. Both security and republican sources now anticipate that there will be further claims and revelations.

The effect on Sinn Fein, stuck in the endless political posturing and talks and preparing for a major electoral onslaught in next year's Dail elections, has been profound in parts of the North. Internal party documents published earlier this year in the Sunday Independent have shown that the leadership is concerned about a drop in what it describes as its "core" support in the North.

This, according to republican sources, has been largely due to disquiet among traditional IRA and Sinn Fein supporters in the North over the events of recent years, including the revelations about Freddie Scappaticci and more recently the outing and murder of Denis Donaldson, a key member of Gerry Adams's inner cabinet as another British agent. Martin McGuinness follows Caoimhghin O Caolain in having to issue a statement saying he was never a police or Garda informant.

According to republican sources in the North, there is now an air of disbelief about what was going on the shadows during the worst of the Troubles when hundreds of IRA members were going to prison while people who avoided prison are nowseen to be benefiting either politically or financiallyfrom their involvement in Provisionalism.

The revelations about Denis Donaldson, who played a vital role in restructuring Sinn Fein both here and in the United States while working as a Special Branch agent, is said to have stunned many traditional supporters including ex-prisoners in the North. The claims about Martin McGuinness have only served to exacerbate this.

One Belfast republican said last week: "We might have expected this. The British didn't rule a third of the world and not learn a few tricks." He added that he and other former associates felt "conned by the whole thing".

- Jim Cusack