The Cambridge Spy Ring was a ring of spies in the United Kingdom that passed information to the Soviet Union during World War II and was active from the 1930s until at least into the early 1950s. None were ever prosecuted for spying. The number and membership of the ring emerged slowly from the 1950s onwards. As far as the general public was concerned, this started with the sudden flight of Donald Maclean (cryptonym: Homer) and Guy Burgess (cryptonym: Hicks) to the Soviet Union in 1951. Suspicion immediately fell on Harold “Kim” Philby (cryptonyms: Sonny, Stanley), but he did not defect until 1963. Anthony Blunt (cryptonyms: Tony, Johnson) and John Cairncross (cryptonym: Liszt), the last two of the group, confessed to British intelligence but this remained a secret for many years, until 1979 for Anthony Blunt and 1990 for John Cairncross. In time the Cambridge Four evolved to become the Cambridge Five.
Don’t forget Roger Hollis, who retired, yet was highly suspect as being a Roosian spy as well, all while being the Director of MI-5. The Brits really do have issues!