The Secret Peacemaker BBC Documentary

Brendan Duddy is an ordinary man from Derry who, for more than 20 years, was at the centre of extraordinary events that eventually led to the historic IRA ceasefire of 1994 and the Belfast Agreement. During that time his identity was kept a closely guarded secret by those with whom he dealt - representatives of the IRA's ruling army council and British intelligence officers from MI6 and MI5. Until now, he's only been referred to as "The Link" or "The Contact", the secret intermediary whose aim was to bring the two sides together to end the conflict. 
 
http://www.imdb.com/title/tt1216506/
 
http://news.bbc.co.uk/1/hi/northern_ireland/7303048.stm