As a young man, Denis Donaldson was good at getting out of scrapes, both as an IRA volunteer and as a legendary seducer. Last week he found himself in a dilemma that tested his plausibility to the limit.

For nearly 40 years this diminutive charmer has been at the heart of the republican movement, first as a teenage gunman and later as Gerry Adams’s most trusted fixer — the clever little man doing the hard work while the big names enjoyed the limelight.

In 2002 he was arrested and accused of being a key figure in what the police claimed was a Sinn Fein spy ring at Stormont, the seat of British government in Northern Ireland. The ensuing scandal caused the collapse of power sharing between Sinn Fein and the Ulster Unionists.

Donaldson also had a hidden life. Last Tuesday, as the winter rain swept through Belfast, his past caught up with him. He was spirited to a furtive meeting with his Special Branch handlers who warned him that his secret was out: he was about to be unmasked as a long-standing British agent.

To his credit he took charge of his own fate. Three days later he confessed at a press conference in Dublin that he had been working for British intelligence and the Northern Ireland Special Branch for at least 20 years.

Reporters were startled. To some it was like a scene from Monty Python. Here was a republican veteran, regarded as one of the Sinn Fein leadership’s most trusted apparatchiks, a man who had been accused of spying against the British, telling them incongruously: “My name is Denis Donaldson . . . I was a British agent.”

He confessed: “I was recruited in the 1980s after compromising myself during a vulnerable time in my life.”

Donaldson’s pre-emptive “outing” of himself is more than one man’s personal drama. For Northern Ireland’s politics it is a huge shock that has unleashed a wave of conspiracy theories. For republicans it is yet more proof that their leadership has been penetrated for years by British intelligence.

For Adams it is a humiliation. The Sinn Fein president said he had suspected that an informant was at work but that Donaldson had never occurred to him as a likely candidate.

People who had known Donaldson for years were stunned by the revelation. A Sinn Fein colleague told Daily Ireland, a pro-Sinn Fein newspaper: “No one, I mean no one, ever pointed the finger of suspicion at Denis Donaldson. He was a loyal party servant. No task was too small for him, no obligation too onerous. He was at the heart of every election campaign.”

Who was this helpful little man and where did his true loyalties lie?

DONALDSON was born in 1950 into a traditional republican family in the nationalist enclave of Short Strand in east Belfast. A beleaguered area surrounded by larger loyalist communities, Short Strand has produced many republican legends.

He joined the IRA in the mid-1960s while he was still in his teens, well before the start of the Troubles. When the IRA split into Marxist Official and traditionalist Provisional wings in December 1969, Donaldson went with the Provos and quickly became involved in their urban bombing campaign. (He served alongside Seanna Walsh, who was chosen by the IRA to read out its statement ending all offensive activities earlier this year.) In 1971 Donaldson was caught during an attempt to bomb a distillery and government buildings and was sentenced to four years in the Maze prison, his first and only jail term.

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