Considered by Vincent Price to be his personal favorite of all of his films, followed closely by O Abominável Dr. Phibes (1971).
This film was shot entirely on location in and around London. No scenes from it were shot in a studio.
Vincent Price fell in love with and married Coral Browne following the film's production, which lasted from July 10 to August 17, 1972. This film was released after Price's March 18, 1973 appearance as the subject of "This is Your Life", his last public appearance with his second wife Mary, who knew nothing yet about his affair with Coral which was set up by Diana Rigg who noticed the chemistry between the two.
When this film was adapted for the London stage in 2005, Diana Rigg's role was filled by her real-life daughter, Rachael Stirling.