Cambridge Five spy ring members 'hopeless drunks'
Members of the "Cambridge Five" spy ring were seen by their Soviet handlers as hopeless drunks incapable of keeping secrets, newly-released files suggest.
Donald Maclean, Guy Burgess, "Kim" Philby and Anthony Blunt were recruited as Soviet spies while at Cambridge University in the 1930s.
There may have been a fifth spy in the ring, possibly John Cairncross.
Documents from the Mitrokhin Archive have been made publicly available for the first time.
The FBI described them as the most complete intelligence ever received.
Major Vasili Mitrokhin smuggled the information out of Soviet archives during 12 years working for the KGB.
He defected to Britain in 1992.
Among the thousands of pages of documents are profiles outlining the characteristics of Britons who spied for the Soviet Union.
They include references to Donald Duart Maclean and Guy Burgess, two of the five men recruited while studying at the University of Cambridge during the 1930s.
A short passage describes Burgess as a man "constantly under the influence of alcohol".
Written in Russian, it goes on to recount one occasion when Burgess drunkenly risked exposing his double identity.
"Once on his way out of a pub, he managed to drop one of the files of documents he had taken from the Foreign Office on the pavement," translator Svetlana Lokhova explained.
Moving on to Maclean, the note describes him as "not very good at keeping secrets".
It adds he was "constantly drunk" and binged on alcohol.
It was believed he had told one of his lovers and his brother about his work as a Soviet agent while he was the worse for wear, the file adds.
The notes also provide an insight into the extent of the group's activity as they helped the KGB penetrate the UK's intelligence network at the highest level.
They describe how Burgess alone handed over 389 top secret documents to the KGB in the first six months of 1945 along with a further 168 in December 1949.
Along with Kim Philby, Anthony Blunt and a fifth man, thought by many to have been John Cairncross, the Cambridge Five passed information about the UK to the Soviet Union throughout World War Two and into at least the 1950s.
After being recruited during their studies, the group went on to occupy positions within the Foreign Office, MI5 and the Secret Intelligence Service (SIS).
Shortly before the end of the war, Philby was promoted to head of the SIS's anti-Soviet section - meaning he was in charge of running operations against the Soviets while operating as a KGB agent.
Defection 'major coup'
Mitrokhin was a senior archivist in the KGB's foreign intelligence HQ and had unlimited access to thousands of files from a global network of spies and intelligence-gathering operations.
He became disillusioned with the Communist Party of the Soviet Union and began handwriting notes from the files which he believed would be of use to foreign intelligence.
His defection was regarded as a major coup and provided an insight into the extent of Soviet intelligence operations throughout the Cold War.
Throughout his life he made it clear he wanted his files opened to the public and following his death in 2004, his family worked with the Churchill Archive Centre in Cambridge to realise this wish.
His handwritten notes made in school notebooks remain classified and some information has been redacted.
But 19 out of 33 box files containing typewritten versions of his notes, all in Russian, can be viewed by visitors to the archive centre.
Cairncross, who had worked in the Foreign Office, was named as a spy by KGB defector Oleg Gordievsky but was never prosecuted.