Colonel Price's house, where the majority of this movie is set, is The Edgwarebury Hotel. This is the same location as the Eaton's house in The Devil Rides Out (1968), also featuring Sir Christopher Lee.
Completed in June 1956, but not released in the U.S. until 1958.
The location for most of the film, The Edgwarebury Hotel would later appear as the hotel used by the lovers in The Rough & The Smooth (1959); the tennis club in School For Scoundrels (1960); Rod Taylor's training ground in The Liquidator (1965); the Eatons' house in The Devil Rides Out (1968); "The Elizabethan Hotel" in The Avengers S7 Episode 20 "Wish You Were Here" (12/2/69); Paul Kirstner's house in Randall & Hopkirk (Deceased) Episode 7 "Murder Ain't What It Used To Be" (2/11/69); "Merstham Manor" in Randall & Hopkirk (Deceased) Episode 9 "The House on Haunted Hill" (16/11/69); Mrs Howe's house in Randall & Hopkirk (Deceased) Episode 14 "Who Killed Cock Robin?" (21/12/69) and the restaurant visited by Strand in Special Branch S4 Episode 12 "Diversion" (2/5/74)
Final film of Ann Greenland.