This was the only movie produced by "Charlemagne Films," which was created by Sir Christopher Lee and Anthony Nelson Keys.
Sir Christopher Lee and Charlemagne Films optioned two other books by John Blackburn, "Portrait of Barbara" and "Bury Him Darkly", which were envisioned as sequels to this movie, with Lee re-creating the role of Colonel Bingham, but it didn't work out. They also optioned some of Dennis Wheatley's books, but only "To the Devil a Daughter" was ultimately made, and by Hammer, not Charlemagne.
The Fox-Rank distributors tried to publicize this movie by offering cash prizes for letters from readers of the Sunday Mercury describing their real-life experiences with terror and the supernatural.
John Blackburn, who wrote the novel on which this movie was based, was displeased with casting of Diana Dors, feeling she was miscast.
It was found that many buildings in Dartmouth were Scottish in appearance and with Dartmoor not far away for the chase sequences it was far easier and cheaper to do the filming there rather than go all the way up to Scotland.