At the height of the Cold War, it was Britain that appeared to be infested with Russian spies and moles. From the 1950s to the 1980s a series of security scandals, from the defections to Moscow of the Cambridge spies Burgess, Maclean and Philby, to the exposure of the Queen’s art advisor Anthony Blunt as a Soviet mole, made Britain in the eyes of her allies the weakest link in confronting Communist Russia.