Unman, Wittering and Zigo
Unman, Wittering and Zigo is a 1971 British thriller film directed by John Mackenzie and starring David Hemmings, Douglas Wilmer and Carolyn Seymour. It is adapted by Simon Raven from Giles Cooper's 1958 radio drama Unman, Wittering and Zigo.
The movie's title was parodied in Little Britain, and by Rowan Atkinson in a very well-received sketch for one of the early Secret Policeman's Ball concerts for Amnesty International.
A new teacher arrives at a school and begins to suspect his predecessor was murdered by the pupils, though his suspicions are written off as paranoia. He sets out to prevent the same fate from befalling him.