The clock – the long-delay timer – nobody is meant to hear is counting down to 2.54am on the 12th October, 1984.

It's attached to a bomb, behind the panel of the bath of Room 629 in Brighton’s Grand Hotel, left there by a man who signed in as Roy Walsh.

Except he's not Roy Walsh.

Who is the man using his name? And how did he go from a childhood in the east of England to attempting to assassinate the Prime Minister and all her cabinet in the biggest assault on a British government since the Gunpowder Plot on 5th November 1605?

The long timer to this moment was set many, many years before.

Written and presented by Glenn Patterson

Series Producer: Owen McFadden
Story Consultant and Sound Design: Alan Hall
Producer: Lena Ferguson
Archive Producer: Fran Rowlatt McCormick
Production Co-Ordinator: Hollie Wallace
Composer: Mark McCambridge
Sound Engineer: Claire Marquess
Mixing Engineer: Mike Woolley
Patrick Magee archive courtesy of Peter Taylor and Whistledown Productions

Executive Producer: Rachel Hooper

A Walk on Air production in association with Keo Films for BBC Radio 4