A blackmail plot. A smear. Or was it both.

Like many of the best thrillers the Heath Caper affair involves sex, spies and blackmail, and an array of possible resolutions that are all eminently plausible yet cannot all be true. Or can they? I have something of a personal window into the worlds this story touches.

It is an old story, that has just resurfaced — with a new twist — in a radio documentary and Sunday Times article by the BBC’s security correspondent, Gordon Corera. The allegation at its centre was first published in a 1970s book by Josef Frolik, a defector from the Czech secret service. Frolik claimed that his spy colleagues had, years earlier, prepared a homosexual honeytrap for a rising young Tory politician, Edward Heath, in the form of a personal invitation from a handsome (and sexually versatile) young Czech organist, to visit and play the famous organ of the Church of St James in Prague.