But, according to the latest details to emerge from the Soviet defector Vasili Mitrokhin, the names of both a former detective sergeant, John Symonds, and the late Labour MP Raymond Fletcher, appear prominently in KGB archives as agents - alongside Melita Norwood - accused of passing crucial nuclear secrets.
Symonds appears to have acted both as an enforcer and "licensed Romeo" who slept with women from foreign embassies to get information. He was taught the techniques of seduction by a beautiful Russian spy. That at least is what Symonds, now 63, grey and balding, says happened. And his astonishing tale tallies with the painstakingly copied archive material that Mitrokhin brought with him when he arrived in the West in l993.
Symonds' story will come as no surprise to Britain's security services. The former detective claims he admitted his KGB involvement to MI5 and MI6, but was dismissed as a fantasist. It was to prove an immensely costly mistake.
Symonds' extraordinary saga began in 1969 when a newspaper exposed him and several colleagues for demanding bribes from criminals, blackmailing them, committing perjury and helping to send people to prison on planted evidence. Criminal charges were brought, but Symonds fled the country before the case came to court.
The fugitive "bent copper" ended up in Morocco, where he claims he worked for a while as a mercenary before being befriended by a Frenchman called Marcel, a Russian agent who directed him towards his KGB masters.
He was recruited as a Soviet agent, given the code name "Scot", and set to work.
It was the kind of work, says Symonds, that many men would dream about - sleeping with pretty women in foreign embassies and getting paid for it. There were even tutorials in the art of love-making. He recalled yesterday: "I was taught how to be a better lover, or perhaps I wasn't a very good one before.
"It was very pleasant. I was taught by two extremely beautiful girls. That was quite an interesting part."
As well as sex, there was travel. On one occasion he was sent to Africa to deliver a blackmail letter to a Chinese diplomat, who was having an affair with a local woman.
There were numerous trips around Europe from his base in Bulgaria, where he had a flat and a mistress provided by the KGB. There was also a visit to Moscow to be personally thanked by Yuri Andropov, KGB boss and later Soviet president, for his part in an operation that led to the demise of the West German chancellor Willy Brandt.
By 1980, Symonds says he had grown tired of his life working for the KGB, despite the money, the gifts and the succession of women.
He was homesick and returned to England where he stood trial at the Old Bailey for corruption. He pleaded not guilty, but was convicted and sentenced to two years' imprisonment.
Symonds says he attempted to atone for his treachery by giving MI5 details about the KGB, including its structures around the world and mode of operations. But he was dismissed as a discredited fantasist. Five years later a partial account of his story appeared in a tabloid newspaper, but it was again dismissed as fantasy by the security services. Critics of the security services say an invaluable opportunity was lost.
Raymond Fletcher spent most of his working life as an MP on the back benches - combining his parliamentary work with writing articles for The Times and The Guardian.
Despite being respected by his peers, the MP for Ilkeston in Derbyshire failed to make much of a mark at Westminster. Former colleagues say they are astonished that he has been named as a spy. According to the Mitrokhin archives, his KGB code name was Peter.
Fletcher's life was riven with contradiction. Although a leading light in the left-wing Tribune group, he was a critic of nationalisation. And while many of his comrades were marching for unilateral disarmament under the banner of the CND, Fletcher advocated the nuclear deterrent. He also played an active part in opposing anti-American motions in the Commons during the early years of the Viet- nam War.
Fletcher's mother was German, as was his first wife, Johanna Ising. She was working for German radio in 1945 when the Russians surrounded the building, but managed to make her way to Lubeck in the British sector where she met Fletcher, who was then serving with the British Army of the Rhine after seeing service with the Indian Army in Burma.
Fletcher's military background led him to take an interest in defence matters and he became a fierce critic of defence spending.
He published a book called Sixty Pounds a Second on Defence, and wrote lyrics for the songs in Joan Littlewood's stage production of Oh, What a Lovely War.
In 1967, Fletcher achieved public office as parliamentary private secretary to Roy Mason, at the time Minister of Defence (Equipment). But he was dismissed just 69 days later by the Prime Minister, Harold Wilson, for abstaining in a critical division on entry into Europe. He did not try for public office again, but became leader of the Labour delegation to the Council of Europe where he was active in the Nato assembly. He also clashed with the left wing of the Labour Party - fighting (and losing) a contest with the Derbyshire councillor David Bookbinder for the Ilkeston seat.
Fletcher was a manic depressive and colleagues say he began, later in life, to drink excessively to alleviate the condition. He died in 1991.
A former constituency colleague said last night: "It is a total shock to hear his name is on the list. None of us suspected anything of this kind and I am not sure what service he could have provided for the Russians."
Melita Norwood, who has admitted she did supply information to the Russians, faced the cameras again yesterday as she strolled in the garden of her home in Bexleyheath, south-east London, dressed in a pale yellow blouse and grey skirt, politely wishing the assembled media "good morning".
She said she had no regrets about her actions, which had been taken in the interests of world peace.