The man convicted of the murder of Lord Mountbatten in 1979 was released under the terms of the Belfast Agreement.

Thomas McMahon (50) had been on daily parole from the Training Unit attached to Mountjoy prison since January 1996. Lord Mountbatten was the Queen’s second cousin and an uncle of Prince Philip. The murder of Lord Louis Mountbatten and three other people took place on the August bank holiday weekend in 1979. The IRA claimed responsibility for detonating the 50lb bomb on the Mountbatten boat, the Shadow V, off Mullaghmore harbour, Co Sligo.

Gardai described McMahon as the bomb-maker at his trial in the Special Criminal Court in November 1979. He was the only man convicted of the murder. He was arrested in a car before the bomb exploded. The driver of the car was acquitted. Lord Mountbatten’s grandson, Nicholas Knatchbull, was one of two 15 year-old boys killed in the bombing. The boy’s 82-year-old grandmother, Lady Brabourne, died later in hospital. The second boy, Paul Maxwell from Enniskillen, had been working on the boat as a summer job. Nicholas’s twin brother, Timothy, and his parents survived the attack.

McMahon, a father of two from Carrickmacross, Co Monaghan, served the first 13 years of his sentence in Portlaoise Prison. In 1985 he was among 11 IRA prisoners who used guns, explosives and fake prison officer uniforms in an unsuccessful escape attempt.