John Profumo was charming, Harrow and Oxford educated and a star of MacMillan's Tory Government. And married.

Christine Keeler had run away from home at 16, became a showgirl in London clubs and was befriended by Stephen Ward, who was alleged to be a Soviet spy. He also 'looked after' a number of girls in London, including Keeler and Mandy Rice-Davies.

In 1961 Profumo and Keeler met at a weekend party at Lord Astor's place in Berkshire. Ward was a frequent visitor there. The couple subsequently had a passionate, but brief, affair.

It would have remained obscure had it not been for Keeler's complex relationships and affairs. She also had an affair with Ivanov, a Muscovite Naval attache and Soviet spy. She alleged that Ward stole sensitive documents from his British 'friends' which were received by Ivanov to pass onto his chiefs in Moscow.

When the story broke in 1962, that a Cabinet Minister had been sleeping with the mistress of a spy, Profumo made the crucial mistake of denying it. He told the House of Commons:

Miss Keeler and I were on friendly terms. There was no impropriety whatsoever in my acquaintanceship with Miss Keeler

10 weeks later he appeared in the Commons again and admitted that he had misled the House in order to protect his family, and he resigned.

The Profumo Affair attracted the attention of the FBI due to the involvement of Soviet spies. Ward was never charged with spying, but was charged and prosecuted with living off immoral earnings. He denied the charge, but committed suicide on the last day of his trial.

Lord Denning undertook an official report on the Affair, at the behest of the Government. It was published in 1963 and concluded that the Government had not acted quickly enough to deal with the Affair, but that there had been no breach of national security.

John Profumo kept a low profile from then onwards, occupying himself with charitable work. Ivanov was recalled to Moscow and never heard of again. Keeler lives quietly in north London.

A photograph of Keeler, naked across a chair, which was publicised when the story broke, became iconic of the start of the swinging Sixties. The scandal seemed to mark the start of an age of increased sexual liberation. Such a story would barely be out of the ordinary today.