Misdefending The Realm: How MI5's incompetence enabled Communist Subversion of Britain's Institutions during the Nazi-Soviet Pact

When, early in 1940, an important Soviet defector provided hints to British Intelligence about spies within the country's institutions, MI5's report was intercepted by a Soviet agent in the Home Office... She alerted her lover, Isaiah Berlin, and Berlin's friend, Guy Burgess, whereupon the pair initiated a rapid counter-attack. Burgess contrived a reason for the two of them to visit the Soviet Union, which was then an ally of Nazi Germany, in order to alert his bosses of the threat and prot...