Nobody seems to have known that a woman called Cynthia Roberts was a Soviet agent in the Cold War, and she herself must have thought she’d got away with it. In 1985 she and her husband defected to Prague, where they are living in an apartment (provided by the Communist authorities of those days, one supposes) in one of those estates whose grimness tells you all you need to know about the Soviet view of people. And there a popular newspaper, the Mail on Sunday, traced her and put the scoop on its front page, without revealing its sources or how it had access to her files in the Czech security services. Apparently quite a few of these files have been destroyed but those remaining have a story to tell.

A veteran Scottish Labour Member of Parliament called William McKelvey is thought to have set her up with a pass and an office in the House of Commons. There she was the secretary of Labour Action for Peace, a rather prominent Soviet front for attacking the nuclear weapons of the West on the pretence of opposing all nuclear weapons (as it continues to do to this day). Through this group, Mrs Roberts came to know influential socialist politicians including future cabinet ministers. In the 1970s she stood unsuccessfully as a Labour candidate, and in 1983 she accompanied Robin Cook, Mr Blair’s future foreign secretary, on a trip to Moscow. Her codename in the Czech security files is Agent Hammer, and her handlers recorded that her self-proclaimed role was “to contribute towards the downfall of capitalism.” After defection, she provided them with character sketches of Mrs Thatcher and other Conservative politicians. She also targeted visiting Westerners, such as diplomats or NATO officials.

“I have nothing to say,” was how Mrs Roberts spoke to the Mail reporter who confronted her. In all probability she was just a useful idiot who never had much to say, and was of little or no real value to the Communists. She would have been really dangerous only in the unlikely event of a Soviet take-over. But what made her do it? Self-importance, venality, credulousness, groupthink, aspiration to power, utopian illusion? She should be brought to account for herself in court, but that will not happen in today’s climate of anything-goes and never-mind. And perhaps it’s some sort of just deserts that she’s 72 now and has to live out her old age in a monstrous Soviet-era block among people whose language seemingly she struggles to speak.