Stuart David Williams was a writer best known for his crime series featuring the banker Mark Treasure and police inspector DI Parry.After serving as a Naval officer in the Second World War, Williams completed a History degree at St John's College, Oxford, before embarking on a career in advertising. He became a full-time fiction writer in 1978. Williams wrote twenty-three novels, seventeen of which were part of the Mark Treasure series of whodunits, which began with Unholy Writ (1976). His experience in both the Anglican Church and the advertising world informed and inspired his work throughout his career.