On 28 May the Director of Russian foreign intelligence, Naryshkin, claimed that "the members of the legendary Cambridge Five in the 1930s came to co-operate with Soviet foreign intelligence largely because they were categorically in disagreement with the policy conducted by London to appease Nazi Germany."
No one would sensibly deny that they opposed appeasement.
But if that were the main reason for their recruitment, why did they then not stop spying once the war was won in 1945 but continued until uncovered by US/UK counter-intelligence?
As their handler in the Cold War, Yuri Modin, noted, they believed in the October Revolution. They were convinced Communists working under cover for the cause that Lenin had fathered
I have an innovative history of the Five, "Moscow's Men", published by Yale University Press in 2027. It is based on the latest releases from the very archive that Naryshkin curates and gives the most complete account of their operations yet in print.