The tones of a balalaika could be heard in the evening air as Guy Burgess and Donald Maclean, members of the Cambridge Five, who spied for the Soviet Union during and after the war, entertained friends at a Moscow flat.

Among the guests was Communist and Daily Worker correspondent Manasseh Lesser who had joined the party in 1935, one of many Jewish youths who saw the Communists as the main challenge to Oswald Moseley’s Blackshirts.

Lesser, who was brought up in the East End, the son of an Orthodox family, wrote under the pen-name Sam Russell and had earlier been wounded while fighting against Franco’s forces in the Spanish civil war.

Papers released by the National Archive show that he was also high on the Security Service’s radar. Information filtered through about the party with the Cambridge spies. A report marked “top secret” pointed out that when someone suggested pictures be taken of Lesser together with Maclean, the spy “furiously refused.”

In a confidential report it, was suggested that Lesser had fallen out of favour with the Russians when he reported that army chief Marshal Georgy Zhukov had been removed from the Ministry of Defence.

According to an intelligence report, Lesser was rebuked by the Soviets while a friend, a Danish Communist journalist, was visited by the KGB and questioned about his and Lesser’s contacts in Moscow.

Lesser went on to report for the Daily Worker from Hungary, Chile, Vietnam and Cuba, where he interviewed Che Guevara during the missile crisis.

One intelligence officer concluded his “nose for news” was combined with the fact that he was “a loyal, dyed-in-the-wool, long-term Party member who has been through the loop.”

An obituary in the Communist daily Morning Star, however, suggested that Lesser had become a fervent admirer of Tony Blair and New Labour in the 1970s.