If Wallis Simpson had not died on the operating table in December 1936, Edward VIII would not have been King of England three years later. He would have abdicated for “the woman he loves,” but now, the throne beckons. If Henry Bannister’s car had not careened off the Colombo back-road in the summer before the war, Cynthia Kirkpatrick would never have found out about The Faction.

It is autumn 1939, and everything in history is just as it was. Except, that is, for the identity of the man in Buckingham Palace and the existence of a secret organization operating at the highest levels of society and determined to derail the war effort against Nazi Germany. From the staff of the newly-founded literary magazine, Duration, hunkered down in their Bloomsbury square, and the country house parties full of renegade Tory MPs, to Tyler Kent, the Embassy cipher clerk with his sheaf of stolen presidential telegrams, the journalist Beverley Nichols deviously at work on an alternative King’s Speech, while a Lancashire lad named Rodney nervously runs errands from his Maida Vale antiques shop to the House of Commons. The Windsor Faction is an ingenious exercise in might-have-been, which assembles a cast of real and imaginary people in a horrifyingly plausible re-invention of history.