By Amanda Killelea It was 1983 and the IRA had just killed six people in London by exploding a bomb outside Harrods. In Northern Ireland, 38 members of the Republican terror group escaped from the Maze Prison, killing three prison service guards. And the second anniversary of IRA hunger striker Bobby Sands’ death in the jail had just passed. That same year – the middle of the 30-year conflict known as the Troubles – Will Britten became the youngest-ever member at 23 of a top-secret unit set up to recruit terrorists as double agents. And Will suggests that the most notorious of them all – coden…