A sensational love affair that "stunned" David Cameron when he was told about it has set Westminster abuzz.
And that was about all the Mail on Sunday told us, claiming it was legally barred from revealing the participants.
Pundits who have been told are divided on the significance of the alleged fling, which some claim could have major political ramifications.
One insider claimed it would be as shocking as former Prime Minister John Major's fling with Tory MP Edwina Currie.
But how will this one stack up against the most sensational political sex scandals of all time?
Political Affairs
Bill Clinton and Monica Lewinsky(01 of11)
Open Image Modal'I did not have sexual relations with that woman' (credit:Getty Images)
John Major and Edwina Currie(02 of11)
Open Image ModalFormer Prime Minister John Major and his Conservative colleague had a four-year love affair when serving as ministers.She later elaborated, telling the Daily Mail: "John Major was a sexy beast. I think his history shows that. He was 19 when he was living with a woman who was 33. Believe me, I did not have to teach that man anything. He was experienced and fun." (credit:PA)
John Prescott(03 of11)
Open Image ModalThe former Deputy Prime Minister had a two-year affair with his secretary, Tracey Temple. (credit:Getty Images)
David Blunkett(04 of11)
Open Image ModalThe former Home Secretary had an affair with married publisher Kimberly Quinn. (credit:PA)
Boris Johnson(05 of11)
Open Image ModalA court recently decided that the mayor's affair with art consultant Helen Macintyre, which resulted in the birth of a daughter, was in the public interest.He was also sacked from the front bench in 2004 over reports of an affair that he initially described as "an inverted pyramid of piffle". (credit:PA)
Robin Cook(06 of11)
Open Image ModalCook was called by Alastair Campbell to warn him as details of his affair with Gaynor Regan were exposed. (credit:PA)
David Mellor(07 of11)
Open Image ModalThe former Tory Cabinet minister fell on his sword after details of his affair with PR girl Antonia de Sancha - complete with toe-sucking and Chelsea kit-wearing - were made public. (credit:PA)
Iris Robinson(08 of11)
Open Image ModalThe MP and wife of Northern Ireland's First Minister, Peter Robinson, had an affair with 19-year-old Kirk McCambley, 40 years her junior, and helped him to start a business. (credit:PA)
John Profumo and Christine Keeler(09 of11)
Open Image ModalProfumo, the Secretary of State for War, quit after having an affair with Keeler in a sensational tale featuring espionage and spying. (credit:PA)
Chris Huhne(10 of11)
Open Image ModalThe Energy Secretary's fling with Carina Trimingham set in chain a series of events that led to Huhne and his ex-wife, Vicky Pryce, being jailed for perverting the course of justice. (credit:PA)
Cecil Parkinson(11 of11)
Open Image ModalIn 1983, the Secretary of State for Trade and Industry resigned after fathering a love child with his former secretary Sara Keays. (credit:PA)