I think the British became aware sooner than the public imagined that here was a man that they could do business with.” He said that Sinn Féin gave him “two sets of accounts books: one for all to see, which showed a steady income from the cumanns through various fundraising, and outgoings… the other set of books told a totally different story. As I gazed at them, I couldn’t believe what I was looking at.

In a new book ‘Thatcher’s Spy: my life as an MI5 agent inside Sinn Féin’ Mr Carlin reveals how he believes Stakeknife saved his life when his cover as a spy in Sinn Féin was blown in 1985. Metaphorically, you don’t put a bullet in the head of your cousin – you just don’t do that,” Carlin told The Herald on Sunday. “There were too many imponderables – the ferry, the support, the safe houses, shooting a policeman who might have had nationalist sympathies, a lot of Glasgow policemen have connections to Ireland.”NARRATOR: This is the story of one man’s secret role in ending one of the most intractable conflicts of the 20th century. He still can’t quite believe it. He adds: "The IRA know I didn't get anyone shot, I didn't go to court as a supergrass and I didn't damage Sinn Fein in any way. Indeed, I spoke at the ard fheis in 1984 about raising funds." Carlin explained: “The IRA’s unstated position was that there were to be no bombs exploding in Scotland during the armed struggle. Even though loyalists such as the UVF [the loyalist paramilitary terror group, the Ulster Volunteer Force] had bombed Catholic pubs in Glasgow in the 1970s, the IRA would not extend their bombing campaign into any part of Scotland.” WILLIE CARLIN: I had come from being a young boy growing up in the Creggan estate now being betrayed by the KGB and British intelligence. Bobby was good to play with, he was a good lad. The Leicester lads were too nice! I sometimes felt some of them were a bit too easy going once the game was over. I felt that they didn’t worry enough about the game, but we did well and I got another promotion under my belt.

If a prosecution goes ahead, the question he said, for him, is: “Do I give evidence against the man who saved my life?” Just last week, it emerged that the Kenova team had sent files to the Crown Prosecution Service in relation to murder, torture, malfeasance in a public office, and perverting the course of justice. Mr Carlin said that Stephen told him: “I have it on very good authority that Lord Chief Justice Lowry has sought and been given such guidance… of course, in this case his legal guidance comes with some private political guidance, too. Ultimately, his life, his actions and the personal consequences he endures because of them stand as yet another triptych to the extraordinary times in which the people of Northern Ireland were forced to make their lives during the Troubles. He dedicates the memoir to all the men, women and children of Derry who lost their lives during the Troubles, and to all those who strove for peace, both openly and behind the scenes.Carlin said: “He went on to explain how valuable the information was when it came to military planning and counter-terrorism on the UK mainland. This information, Stephen stressed, would calm the minds of those anti-terrorist commanders in Scotland. He was clearly delighted.” They told me they didn't want me to inform on the IRA. They warned me to stay away from them, because if I passed on information to my future handlers, the organisation would soon find out what I was doing," says Carlin, who adds that he decided to write the book, Thatcher's Spy, because he wanted to record his part in getting Sinn Fein from where they were in the 1970s to where they are today.