Fox, an apprentice coach builder from the Falls Road in Belfast, Northern Ireland, joined the IRA in 1969 aged eighteen.
He explained his motivation for joining the IRA in a 1998 interview with the Irish News, stating: "I was almost shot in a gun attack at Norfolk Street.
[7] In 2005 Fox joined the IRA's Army Council replacing Brian Keenan who resigned due to ill-health.
Fox resigned in September 2006 after accusing Gerry Adams and Martin McGuinness of "undemocratically" controlling the organisation, and later became involved with Éirígí.
Fox made a formal complaint regarding his treatment to the Investigatory Powers Tribunal, a body set up under the Regulation of Investigatory Powers Act 2000 to investigate complaints against MI5 and other law enforcement agencies.