They do not want the dirty secrets out and want to protect their agents. The brits had completely infiltrated the IRA prior to the peace process, so numerous were their spies that it resulted in some spies killing other spies to protect the more valuable asset eg Stakeknife killing Frank Hegarty (both Brit agents) on the order of Martin McGuinness. Hegarty gave up the Libyan arm imports but Stakeknife had to be protected at all costs At one stage MI5 had infiltrated all the IRA up to the top with the exception to south Armagh which they found inpenetrable. They ensured that both McGuinneess and Adams were not assassinated or deposed (The SAS took out Lynagh) and that both were elected. MI5 always had contact routes with the IRA even without the Knowledge or consent of Thatcher and when Blair was elected these contacts were put to good use. Perfidious Albion has always been very good at these dark arts, they have had plenty of practice, but the full story of British intelligence in NI Ireland will never be written as smokescreens is the nature of the game but I think it would put Bletchly Park in the shadows.
