The movie version features Alastair Sim as the headmistress (in drag) and her brother, a bookie. The plot revolves around a horse race: one of the girl's father is a sheik with a horse that is sure to win, and Sim (the bookie) has a horse running against him. It comes down to a battle between the vicious little girls in the fourth form backing the sheik's horse, and the sexier sixth form backing Sim's.
The fourth form have several advantages:
- They are younger and more evil
- The headmistress has bet the school funds on the sheik's horse
- They have their own spiv: A shady character with a pencil thin moustache named Flashy 'Arry. He is their personal blackmarketeer, bookmaker and bootlegger (he sells the booze they make in chemistry lab)
Other than that, the film is a little flat. We don't get much definition on any of the girls, the disreputable teachers (even the Morticia-esque jailbird) or the undercover policewoman investigating the school (although she has a great loping stride as the games mistress). Maybe the film works better if you've read the books. Anyway, I felt a little left out, like there was a great joke being told, but I'm not getting the punchline.