Brian Keenan was director of IRA terrorist operations in England in the mid-1970s. According to Jonathan Powell, Tony Blair’s former chief of staff, Keenan was “the single biggest threat to the British state” in that decade.

Keenan, who received an 18-year prison sentence in 1980 for conspiring to cause explosions, was also a leading figure in the Provisional IRA in Northern Ireland itself, and a member of its “army council”. Although he endorsed the peace process, and was a key player in decommissioning negotiations, he remained an unrepentantly militant Irish republican and Marxist, who believed the ballot box, as opposed to the bullet, to be a temporary means to achieving a united Ireland.

He may have seen himself as a working-class revolutionary, but he was simultaneously a sectarian bigot. “Keenan believed that the only way, in his words, to put the nonsense out of the Prods was to just hit back much harder and more savagely than them,” recalls the IRA informer Sean O’Callaghan. It was Keenan who recommended to Seamus Twomey, then the Provisionals’ “chief of staff”, that the UVF’s random anti-Catholic assassinations should be met with reciprocal acts. The result was the IRA’s attack in Kingsmill, South Armagh, in January 1976, in which ten Protestants were murdered in a machinegun attack.

Brian Keenan was born in Swatragh, Co Londonderry, and raised in Belfast. His father, Harry, was in the RAF, and had won a commendation for bravery for helping to save the lives of a crew of a bomber that had crashed on take-off.

Keenan moved to England in his late teens, and worked as a television repairman in Corby, Northamptonshire. He developed an interest in radical politics, befriending members of the British Communist Party. He took an interest in Palestinian politics and admired the PLO. He was involved in a pub brawl in which he damaged a cigarette machine, so that the police had his fingerprints on file.

He returned to Northern Ireland at the beginning of the Troubles, working at the Grundig factory in Belfast. An intelligent man, able to speak several languages, and a committed trade union agitator, by 1970 he had joined the Provisional IRA. He read Bakunin and Gramsci and might have joined the Marxist-inclined Official IRA had he not correctly assumed that the Provisional IRA was going to command greater support from Ulster’s Nationalist community.

By August 1971 Keenan had become “quartermaster” in the Provisional IRA’s Belfast “brigade”, which was to be responsible for numerous bombings and atrocities in the years to come. His sympathy for the Palestinians and for Marxist causes led him to make political contacts in Libya, Lebanon, Syria and East Germany, from whom he secured arms on behalf of the Provisional IRA. In 1972 he visited Tripoli to visit Colonel Gaddafi with this aim.

By the beginning of 1973 Keenan had become the Provisional IRA’s “quartermaster general”, taking responsibility for its bombing campaign in England, which had begun the year before. He was arrested in the Republic of Ireland in 1974 and served a 12-month prison sentence.

On release, Keenan became instrumental in the restructuring of the IRA, which in the mid-1970s was effectively being defeated by measures introduced by the Labour Government’s Northern Ireland Secretary, Merlyn Rees. Gerry Adams had masterminded the idea of restructuring the organisation into cells. Keenan and Martin McGuinness successfully sold the idea to the IRA “army council”. One IRA member remarked that “Keenan was really John the Baptist to Adams’s Christ”.

Returning to the mainland, Keenan was instrumental in the activities of what became known as “the Balcombe Street gang” (named after the Central London street where they were besieged and eventually apprehended in December 1975) that carried out 50 bombings and shootings in London.

Keenan’s IRA unit was based in Crouch End, North London. When the police eventually raided its headquarters, they discovered crossword puzzles in his handwriting and fingerprints that matched those found both on the cigarette machine in Northamptonshire and on bomb parts recovered in London.

A warrant was issued for his arrest in 1975 and in March 1979 he was captured by the RUC while travelling to Dublin. Extradited to England, he was defended by Michael Mansfield, QC, at the Old Bailey. He was was convicted of 18 counts of planning terrorist acts, including six killings.

While in Leicester Prison, in 1982 Keenan wrote a letter endorsing Gerry Adams’s decision to stand for election to the Northern Ireland Assembly. He also supported Sinn Fein’s decision to drop its abstention policy from the Dáil, the Lower House of the Irish parliament. Yet Keenan, like Danny Morrison, who in 1981 famously told a Sinn Fein conference “will anyone here object if, with a ballot paper in one hand and an Armalite in this hand, we take power in Ireland?”, believed constitutionalism was not a betrayal of the Irish Republican ideal, but merely one of its means to an end.

He was released in June 1993 and by 1996 he was one of the seven members of the IRA’s “army council”. Like McGuinness and Gerry Kelly, he had a formidable reputation thanks to his past activities in the IRA, which made his backing for the peace process so influential. His role was to assure hardliners that the 1998 Belfast agreement was not a surrender, and to prevent members defecting to republican splinter groups. He acted as a go-

between with the Independent International Commission in Decommissioning, standing down in 2005 because of ill-health.

Throughout this process he nevertheless adhered to his long-held principles. As he had said in 1996: “Do not be confused about decommissioning. The only thing the republican movement will accept is the decommissioning of the British state in this country.”

In May last year, gravely ill with cancer, he attended Stormont to witness his old enemy Ian Paisley being sworn in as First Minister of the Northern Ireland Assembly.

Keenan is survived by his wife, Chrissie, two sons and four daughters.

Brian Keenan, Irish republican, was born in 1941. He died of cancer on May 21, 2008, aged 67