Tower of Evil (1972)
Tower of Evil, also known by the title Beyond the Fog in the United States and Horror of Snape Island and Horror on Snape Island in Canada, is a 1972 British horror film. The film is regarded by horror fans as being ahead of its time, as it crosses old world Gothic themes (dark setting, mythical superstitions, gloomy atmosphere) with many elements of the modern slasher film (elusive killer, bloody murders, sexually active characters as victims). The film was shot at Shepperton Studios in Shepperton, Surrey, England in 1971.
More at Wikipedia.