The house is Oakley Court, used for exteriors in several Hammer films, and for The Rocky Horror Picture Show (1975). It was later turned into a luxury hotel.
The screenplay is credited to Diana Daubeney, director José Ramón Larraz's wife Diana. According to Larraz and producer Brian Smedley-Aston, she didn't actually write a word of it. She was credited because, as a British citizen, she filled a UK production quota.
Rumors abound about a missing scene in which Fran and Miriam are seen inside the caravan of John and Harriet. This rumor is borne out by production stills and a vague recollection by producer Brian Smedley-Aston that it was, indeed, shot.
The presence of the suspicious old man at the inn at the beginning is an allusion to the suspicious hotel clerk in "Daughters of Darkness", another outstanding vampire lesbian cinematic outing.
Marianne Morris said in a 1994 interview that her 17 year old daughter was very embarrassed when her friends said they found a copy of the movie and watched her fully naked mom have lesbian sex. Morris thought it was funny.