Roy McShane, who was exposed last week as a British agent, took a particularly hard line against touts, as befitted a former member of the IRA's counter intelligence wing, the once feared "nutting squad."
Regulars in the Trinity Lodge Social Club can recall his fury when, at the end of 2005, his friend Denis Donaldson was exposed as a British agent in a press conference organised by Gerry Adams, the Sinn Féin President. As Adams' driver McShane made great show of his anger at the depth of betrayal by Donaldson, at the time Sinn Féin's Chief of staff.
"He was literally spitting with rage, I mean the saliva was going into other people's drink, he wanted Donaldson stiffed, what he wouldn't do to a bastard like that" said one former republican activist.
"Roy always took that sort of line. If he saw the family of someone who was suspected of being an informer he could be really nasty to them. It shows that it is not the guys who sit in the corner eary wigging on your conversation that you need to worry about, it's the ones up waving a tricolour and shouting the odds who are the touts."
And so it had turned out in the case of the nutting squad. The all powerful internal unit which was responsible for rooting out informers within the IRA had to be wound up after it became clear that it was too heavily infiltrated by the RUC and British Intelligence to be of any use in combating them. It has left behind a mess which is an embarrassment both to the British government, which prefers to keep its methods secret for use in other conflicts, and the republican leadership who are starting to look like fools.
Freddie Scappaticci, the nutting squad's one time second in command, was the British military intelligence's most prized agent, known to his handlers as Stakeknife. He has now fled and his former boss, Brigadier John Gordon Kerr, went on to become British military attaché in Beijing. Agent handlers in Kerr's Force Research Unit (FRU) were redeployed to Iraq and Afghanistan where they use the methods honed on the IRA and loyalist para-militaries to infiltrate and manipulate new enemies.
Still more of them work for MI5 at its new HQ in Palace Barracks, Holywood, outside Belfast, where they continue to spy on dissident republicans and what remains of the IRA. McShane was probably staying there when he phoned his estranged wife to tell her he was in protective custody last Thursday.
The leader of the nutting squad, John Joe Magee, died under a heavy cloud of suspicion that he too was a British agent. "The Hawk", another well known IRA intelligence officer who had had several miraculous escapes from the clutches of the law, is also suspected of secretly "smiling at" Special Branch. The Hawk even ran agents for the IRA within the loyalist paramilitaries, the most famous of which was Jimmy Craig, who directed the UDA's building site rackets.
Craig was murdered by his comrades when they became convinced that he had fed the Provos with the names of anyone who accused him of stealing money in return for permission to operate extortion rackets in republican areas. The dead allegedly included Lennie Murphy, the leader of the Shankill Butcher gang, and John McMichael, the UDA's number two, who was on Craig's trail when the IRA blew up his car with a booby trap device.
McShane's exposure this month is, if possible, a still deeper blow. When the nutting squad broke up he was one of the trusted ones to survive the debacle. He was regarded as above suspicion and re-allocated to drive Adams and McGuinness during the most sensitive periods of the peace process.
The operations he had been involved in, possibly in an unsuccessful effort to thwart them, were such that nobody believed he could possibly have been working for his stated enemy. He was allegedly involved in the adduction of Thomas Niedermayer, a Grundig manager who died when he was hit on the head with a pistol by his IRA captors for making too much noise. Would the kidnapped businessman have been rescued with McShane's help had he not resisted his captors?
Former IRA members say McShane was also implicated in a nutting squad investigation which resulted in the death of two fellow agents.
They were Catherine and Gerard Mahon, a husband and wife who at the time lived hear him in Norglen Crescent in the Turf Lodge estate. The duo, who were murdered by the IRA on 8 September 1985, had allowed their flat to be used as an IRA arms dump and safe house for meetings and had allegedly passed on details to the police. They were also alleged, by the IRA, to have been responsible for the capture of a 30lb bomb and the capture of three INLA men.
They are widely believed to have been sacrificed to protect the cover of Joseph Fenton, an estate agent, who also provided the IRA with safe houses, and who was himself "executed" by the IRA after being interrogated by Scappaticci in 1989.
The couple, who lived on benefits, had allegedly worked for the police for £20 a week to escape prosecution for unpaid fines. Were the Mahons innocent or were they pawns in a dirty war where the priority was to ensure the promotion of more important agents in the IRA? That is a question that will have to be answered by the Historic Inquiries Team, a police unit set up to investigate all the troubles deaths, who have set up a special section to deal with the "nutting squad" murders and who have interviewed Scappaticci on a number of occasions.
No doubt they will want to talk to McShane too.
Fred Holroyd, a former British Military Intelligence officer, once told me that during training he had been told "the best way to defeat the enemy is to be the enemy."
The more we learn about security force infiltration of the IRA and Sinn Féin the more intimate the relationship appears. We already know that when McShane was driving Adams the car was bugged, possibly McShane made the vehicle available for the five foot device to be built into the roof.
That bugging was on foot of a warrant signed by Mo Mowlam who also authorised the tapping of Martin McGuinness's home phone, even as she chatted indiscreetly to him, confiding her differences with Tony Blair and calling him "babe". I was arrested for exposing that particular piece of surveillance and when I asked Mowlam if she had authorised it she laughed and said "you know I authorised so many," speaking of her warm regard for McGuinness.
Adams phone was almost certainly bugged too. Certainly he found a listening device built into the rafters above his office in Sinn Féin's Connolly House headquarters in Belfast. Another was discovered above the living room of Paula McManus, a secretary who worked in his West Belfast constituency office and who was friendly with Martin Lynch, the adjutant general of the IRA at the time.
Adams has referred to the relatives of senior republicans being targeted by the security services for recruitment and some people personally very close to the leadership are under serious suspicion of succumbing to the advances.
Many who worked as agents, like Willie Carlin who reported on Sinn Féin in Londonderry for years, believe that they did good service to the cause of true republicanism by helping steer the organisation into politics. British spy masters, like Michael Oatley the MI6 officer known as Mountain Climber, express admiration for the republican leadership, others, like the late Brian Fitzsimmons who headed Special Branch until his death, believed that the endgame would be a united Ireland on agreed terms once the IRA campaign ended.
It's a murky picture and it is clear is that there is a common interest between Sinn Féin and the British government is keeping it under wraps. Gerry Adams used to hit the roof when British spy plots were revealed. Last week he said he wasn't worried about agents within Sinn Féin.
It's a remarkable political journey. He should consider entitling his next book "How I Learned to Stop Worrying and Love the Brits".