Suspicion immediately fell on Kim Philby (1912–1988, codenames Sonny, Stanley), who eventually fled to the Soviet Union in 1963.
[5] Maclean and Burgess were reportedly seen by their Soviet handlers as "hopeless drunks" as they had a hard time keeping their secret occupations to themselves.
It is said that one time, while highly intoxicated, Burgess accidentally dropped one of the secret files he had taken from the Foreign Office while leaving a pub, jeopardizing his second identity.
[10] A book review in The Guardian of Stewart Purvis and Jeff Hulbert's biography of Burgess included this conclusion: "[leaving] us all the more astonished that such a smelly, scruffy, lying, gabby, promiscuous, drunken slob could penetrate the heart of the establishment without anyone apparently noticing that he was also a Soviet masterspy".
Harold "Kim" Philby was a senior officer in Britain's Secret Intelligence Service, known as MI6, who began to spy for the Soviet Union in 1934.
[13] In the later 1950s, Philby left the Secret Service and began working as a journalist in the Middle East, writing for The Economist and The Observer.
He served as an MI5 member and supplied secret information to the KGB, while also providing warnings to fellow agents of certain counterintelligence that could potentially endanger them.
By 1979, Blunt was publicly accused of being a Soviet agent by investigative journalist Andrew Boyle, in his book Climate of Treason.
In November 1979, Prime Minister Margaret Thatcher admitted to the House of Commons that Blunt had confessed to being a Soviet spy fifteen years previously.
The term "Five" began to be used in 1961, when KGB defector Anatoliy Golitsyn named Maclean and Burgess as part of a "Ring of Five", with Philby a 'probable' third, alongside two other agents whom he did not know.
At the time of Golitsyn's defection, Philby had already been accused in the press and was living in Beirut, Lebanon, a country with no extradition agreement with Britain.
Golitsyn's reliability remains a controversial subject and as such, there is little certainty of the number of agents he assigned to the Cambridge spy ring.
The manuscript indicated that he regretted having passed information to the Soviets because of the way it eventually affected his life, that he believed that the government would never reveal his treachery and that he had dismissed suicide as "cowardly".
[17] Christopher Andrew felt that the regret was shallow, and that he found an "unwillingness to acknowledge the evil he had served in spying for Stalin".
He moved to the Treasury in 1938 but transferred once again to the Cabinet Office in 1940 where he served as the private secretary of Sir Maurice Hankey, the Chancellor of the Duchy of Lancaster at that time.
The news was widely publicized leading many to surmise that he was in fact the "fifth man"; that was confirmed in 1989 by KGB agent Oleg Gordievsky who had defected to Britain.
[20] His designation as the fifth man was also confirmed in former KGB agent Yuri Modin's book published in 1994: My Five Cambridge Friends: Burgess, Maclean, Philby, Blunt, and Cairncross.
After the book was published, former KGB controller Yuri Modin denied ever having named Rothschild as "any kind of Soviet agent".
[26] For unknown reasons, Prime Minister Alec Douglas-Home was not advised of Anthony Blunt's spying, although the Queen and Home Secretary Henry Brooke were informed.
It was only in November 1979 that then-PM Margaret Thatcher formally advised Parliament of Blunt's treachery and the immunity deal that had been arranged 15 years earlier.
[27] A 2015 article in The Guardian discussed "400 top-secret documents which have been released at the National Archives" and indicated that MI5 and MI6 had worked diligently to prevent information about the five from being disclosed, "to the British public and even to the US government".
[28] A 2016 review of a new book about Burgess added that "more than 20% of files relating to the spies, most of whom defected more than 50 years ago, remain closed".
In conclusion, the review stated that "the Foreign Office, MI6 and MI5 all have an interest in covering up, to protect themselves from huge embarrassment" and that "more taxpayers' money is spent by Whitehall officials in the futile attempt to keep the files under lock and key for ever".
A summary of the documents indicated that they showed that "inaction and incompetence on the part of the authorities enabled Guy Burgess and Donald Maclean to make their escape to Moscow".
They indicated that the government had intentionally conducted a campaign to keep Kim Philby's spying confidential "to minimise political embarrassment" and prevented the publication of his memoirs according to a report by The Guardian.