Based in an Edwardian townhouse in a quiet street behind Harrods, the mysterious SFC is at the forefront of a campaign to protect the last remaining secrets of the special forces units.
Adrian Weale, a leading military historian, was expelled after a 40-minute dressing down by a disciplinary committee of the club - which only takes members who have served in special operations or intelligence units. Mr Weale, 33, acted as an adviser to Sarah Ford, a female special forces operative, whose book One Up, A Woman in Action with the SAS, caused great controversy when it was published in March.
The behind-the-scenes account of a woman's experience of special forces operations in Northern Ireland proved too much for some members of the SAS establishment.
Mr Weale was accused of conduct "construed as incompatible with membership" and summoned before the SFC committee this month. "The hearing was Kafkaesque, none of them would introduce themselves," he said. "The complaint had nothing to do with breaches of national security but that the book had upset people who might be drinking next to me in the bar."
He said that the book had been closely vetted by the Ministry of Defence and did not disclose operationally sensitive information. The problems, he said, were caused by the book's disclosures on infidelity. "It was embarrassing for people who were cheating on their wives."
Colonel Edward Toms, chairman of the club, and nine unidentified committee members, warned Mr Weale that his actions had upset other members. They refused to tell him exactly what the complaint against him was or who had made it.
Mr Weale, who has been a member of the club for three years, said: "I am the only person who has ever been thrown out for involvement in a book. It is a slur on my character and integrity."
Mr Weale joined the Intelligence Corps as a cadet and after Sandhurst was posted to Northern Ireland. He later worked for Naval intelligence and was deputy chief of British intelligence in Belize, working alongside MI6 and the CIA. He has written four military books, the subject matter of which include war crimes by British troops in the Falklands and Britons who fought for the Nazis in the Second World War.
The rush of books on the SAS began with the publication of Storm Command by General Sir Peter de la Billiere, the former SAS soldier who was the most senior British officer in the Gulf War. It was followed by Andy McNab's Bravo Two Zero, which gave a first-hand account of an eight-man patrol behind Iraqi lines, and made an estimated pounds 5m. Mr McNab and General de la Billiere have retained their SFC membership.
Earlier this year, the Ministry of Defence wrote to two dozen military authors, banning them from visiting army bases in case they attempted to gather material for future books.
Mr Weale, however, has already completed his next book about the SAS. Secret Warfare - Special Operations Forces from the Great Game to the SAS aims to be a definitive study of special forces and will be published later in the summer.
Chris Moorhouse, assistant secretary of the club, said: "What happens in the club is purely confidential to the club. Mr Weale met the committee and they explained it all to him."
The Special Forces Club was set up in 1946 by members of Special Operations Executive which fought in the Second World War. The club motto is "The Spirit of Resistance".
Mr Weale said: "The club was set up to embody the spirit of resistance to the likes of Nazi Germany and Imperialist Japan and yet goes round chucking people out for books on the basis of an anonymous denunciation. I find that a supreme irony."