Seventy-five years ago this week a revolution in crime-writing began when Knopf published The Big Sleep, Raymond Chandler's first novel. Reviews in 1939 were wary and unenthusiastic, however, and only gradually was it recognised that Chandler had pulled off a bold fusion of highbrow and lowbrow – much-applauded by authors such as WH Auden, Graham Greene and Evelyn Waugh, but also much-imitated by fellow chroniclers of murder.