Though a Marxist during most of the 1930s, the Hitler-Stalin Pact turned him from communism and led him to enlist before the UK entered the war.
In 1956, a series of articles appeared in The People that described their anonymous author as a "Most intimate friend, a man in a high academic position".
"[6] Rees sat on the Departmental Committee on Homosexual Offences and Prostitution and played an influential role in getting gay men's testimony heard.
The Hitler-Stalin Pact led him to take a strong anti-communist stance, which he put into writing by 1948: "A spectre is haunting Europe."
The words are more true today than they were when two hopeful young men wrote them almost exactly one hundred years ago.
[12] In her memoir, Rees's daughter Jenny Rees wrote that her father was fascinated by the Hiss–Chambers case, which marked a sharp divide intellectually between him and Burgess: 'Hiss was certainly guilty; he was precisely the sort of person who was capable of carrying out the systematic program of espionage which Whittaker Chambers, so improbably as it seemed, had accused him; and only a communist could be capable of such a feat...' But according to Guy, it was Hiss, not Chambers, who deserved the admiration.
[5]Rees seemed acutely conscious of the parallels between Hiss's case and that of the Cambridge Five (specifically Burgess) when he wrote, "I have no intention to be the British Whittaker Chambers".
[citation needed] Rees told Andrew Boyle, author of The Climate of Treason, his reflections on his conversations with Burgess at All Souls College.
[16] Boyle's revelations in the Daily Mail led Prime Minister Margaret Thatcher to announce to the House of Commons in 1979 that the security services had long known that Blunt was a spy, due to Rees's warnings to the security services the weekend that Burgess and Maclean fled to Russia.
The file also says that he supplied no information to the Soviets and abandoned his communist affiliation at the outbreak of World War II.