Watched late at night this is an effective old style psychological horror very much in the vein of Night of the Demon. In fact it seems to take much inspiration from the more famous movie. The story itself is not as good though, and its contrivance shows in the very first scene, with Wyngarde lecturing his students on the paranormal, which, as far as I know, has never been a degree course, even in its heyday in the Elizabethan and Jacobean era.
This obvious piece of film hokum should be overlooked, however, as the movie soon folds out into a pleasingly tense pschological suspenser. You do have to remember you are in a movie world, where successful middle class professionals are also practising witches, as though it's as normal as knitting jumpers for a hobby, but the film does evolve nicely into a neat, sinister tale of jealousy and wicca dabbling.
Lovely clear black and white photography distills that very nostalgic middle England of the early 60s, nice country houses, a lovely Gothic college building, classy tweed jackets and skirts, clipped English accents, a drinks cabinet in every room and clouds of cigarette smoke. This is all as much part of the joy of watching this film as the hokey story itself. But it is very well directed and produced and there isn't much slack here, it is a clean, professional piece of work and it is effectively creepy in parts. The tension builds very nicely, and it has some very good special effects for its time, in the fine climactic ending.