The bloodline of a joke is never easy to establish. If you want to know, word for word, exactly what part David Croft played in the history of television comedy only Jeremy Lloyd and Jimmy Perry could ever have told you and they probably couldn't now – so mysteriously alchemical is a successful writing partnership. What we do know is that the DNA of the classic British sitcom would be utterly different without him. In company with Lloyd and Perry he mastered the ensemble comedy of types, a kind of sitcom which has passed out of fashion in recent years, with the rise of more documentary styles, but which absolutely dominated the Seventies and Eighties.
Croft learnt his writing skills in British pantomime, and the staples of that kind of theatre – innuendo, slapstick, a raucous silliness – are apparent in all his shows. But they wouldn't have done as well as they did (or lasted as long) without something else too. A striking number of his comedies were period pieces but their inverted power relationships and internal sparring covertly addressed changing attitudes to class and social attitudes. John Le Mesurier told the story, against himself, of being sent the script for Dad's Army and being on the point of passing on it, because he assumed he'd be cast as the Captain. It was only when he realised that Arthur Lowe was to be a superior with an inferiority complex that he saw the possibilities. Croft then wrote to the strength of his performers in ways no actor could resist.
He may well get a dedicated memorial of his own some day – besides the boxed sets and the fan websites and the occasional repeat. But he already has some telling tributes to his talent and influence. You can see an oblique one in Thetford, where a full size statue of Captain Mainwaring was unveiled last year. It's a statue of a comic invention so successfully rendered in three dimensions you could cast it in bronze.