Royston Cave in Royston, near Cambridge, is believed to have been used by the Order of the Knights Templar as a secret meeting place. It was discovered by accident in the middle of the 18th century and is full of carvings.

Historic England said the "mystical carvings" had been added to its Heritage At Risk register because they had "steadily deteriorated due to water penetration and worm activity".

Cave manager Nicky Paton says he believes it is "call to action" and will bring about the "needed conservation" to stabilise the carvings.