The Caynton Caves, hidden in dense woodland near Wolverhampton, have a rich history stemming back to the 17th century when they were apparently carved out of sandstone by followers of the Knights Templar.
In the past, the landowners have tried to be accommodating when sects, good or evil, have asked permission to use the site.
Their patience began running thin when, over Christmas, they found the caves had been filled with candles, sinister symbols scrawled on the walls and rubbish.
But the final straw came when they answered the door to two red-faced warlocks who had the cheek to ask for the return of their robes which had been used in the black magic ceremony.
Dominic Wass, an urban artist who has a workshop on the site, said: ‘There’s definitely some strange stuff gone on down there. It’s surreal to have two warlocks knock on your door, but at least they asked.’
Inside the caves, mystic sigils (seals) competed for crowded wall space with more modern scrawled messages, written by youths who have turned the temple into a drinking den
The site ranks alongside Castle Ring, a public Stone Age monument near Cannock Wood, Staffordshire, which has become a hotspot for Druids.
Solstice and Halloween pose particular problems at Caynton. One Halloween bonfire party for local children was interrupted when trespassing worshippers, alerted by smoke, spilled out from the cave.
Mr Wass said: ‘Very little is known about why they are there. There are all kinds of stories. We were told they were dug by followers of the Knights Templar (a sect dating back to the days of the Crusades). They wanted a place where they could worship without being persecuted. It must have taken them a long time to create. We’ve also been told that a landowner hid slaves down there. Slavery was illegal by then and he’d hide as many as 60 down there.’
Some believe the grotto is more recent, dug out in the 1850s by a wealthy family as a folly.
One website, devoted to Britain’s hidden treasures, states: ‘It consists of a series of passages and chambers, with niches for candles, and the carving of the rooms is quite professional. It’s a creepy place and is rumoured to have been used in the 1980s for Black Magic rituals.’