“The Fourth Protocol” by Frederick Forsyth

It is a time of political unrest in Great Britain. And behind the Iron Curtain an insidious plot is being hatched, a plan so incendiary that even the KGB is ignorant of its existence—“Aurora,” the sinister brainchild of two of the world’s most dangerous men: the general secretary of the Soviet Union and master spy Kim Philby.
The wheels are in motion, the pawns are in place, and the countdown has begun toward an “accident” that could change the fact of British politics forever and trigger and collapse of the Western alliance.
Only British agent John Preston stand any chance of breaching the conspiracy. Through plot and counterplot, from bloody back streets to polished halls of power both East and West, his desperate investigation is relentlessly blocked by deceit, treachery, and the most deadly enemy of all…time.