The Lost Valley

Egyptologist and 'witch-cult' hypothesiser Margaret Murray once provided expertise to Jacques Tourneur while the director was making his classic 1957 folk-horror movie (well, I think it is) Night Of The Demon . Murray's entry on 'witchcraft' in the Encyclopaedia Brittanica famously remained in place for a whopping 40 years, spreading her interpretation of the subject far beyond the world of academia, where her ideas were received skeptically. Such was her fame as an expert on the occult that movies studies came to her door, looking for advice on how to portray magic and curses.  See? Folk-horror.

The great Dennis Wheatley (stop laughing) gives a brief mention of Lost Horizon in his own lost race novel The Man Who Missed The War when he says about that book's mythical Antarctic kingdom: ' No, this is not Shangri- La. There are no temples here, no wise men seeking to preserve all the accumulated beauties of our civilisation from destruction ... '