From The Armchair Detective, May 1975, newly arrived on archive.org…
The Conjurers by Marilyn Harris. The evil is connected with ancient megalithic circles [near] a village called Dormeshaven, close to Avebury and Stonehenge in Wiltshire [southern England]. Miss Harris uses themes and incidents that smack very much of some of H.P. Lovecraft’s work [and] the tender stomached may find The Conjurers a bit much at times. [Sadly the Oklahoma-based American] Miss Harris has failed to catch the atmosphere of Britain as a Briton.
The 1974 Random House novel is now on Archive.org.