The Satanists

"The Satanists was to be a Tyburn movie, directed by Freddie Francis and starring Peter Cushing. Co-stars were meant to be Trevor Howard and Joan Collins. Supposedly it was based on Wheatley's The Satanist, but this is quite hard to believe. The copyright of this is by Tyburn Publishing, an arm of Tyburn Film. Everything was on the go, but then financing collapsed and it was never made. But apparantly the novelization was already done. It was published a few years later." [info from: https://vaultofevil.proboards.com/thread/7250/robert-black-satanists]

Price on back cover of richarddalbyslibrary.com copy; other prices: Australia $2.45, New Zealand $2.30, Canada $2.25.