In the St Trinian's films, Harry is a long-term associate of the girl pupils, a Cockney involved in all sorts of shady dealings.
[3] As an adult, Harry is one of the few whom the pupils trust: he helps to bottle and sell their gin, distilled in the school chemistry lab, and places bets on race horses for them.
Harry also runs the St Trinian's Matrimonial Agency for the teenage Sixth Form girls, setting them up with wealthy men.
Harry appears to be quite well known in the criminal community, another crook (Lionel Jeffries) referring to him as "riff-raff".
The main plot of The Belles of St. Trinian's centred on the kidnapping of a race horse and featured Sid James of Carry On fame as a shady bookmaker.