Was very lucky to have the chance to see this one! Amazing little place, very quirky only consisting of 3 rooms and very small adjoining tunnel but is very interesting all the same. I believe the correct term for it is a “Folly” in basic terms im from the understanding that it was a way for rich people to show their affluence.
The grotto, was believed to have been part of a hall that was built in 1752 (now demolished) and is Grade II Listed and due to the rumoured nature of its existance its possible that the grotto its self was a later edition. Now sealed this hidden gem will now only be seen via the pictures taken.
Grotto. Circa late C18. Carved from red sandstone bedrock with
seams of gravel. A series of interconnected underground chambers.
A plain roughcast arched portal in a steep bank, leads to an
aisled antechurch with groin vaults, at the end of which is a
rotunda (a circular chamber) with a colonnade of 6 Tuscan columns
with plain capitals and abaci supporting an entablature and saucer
shaped dome. At north end of antechurch a vaulted passage turns
north, with small saucer-shaped dome over corner, into antechamber
with arcaded walls, cornice and hipped ceiling. From the ante-
chamber a tunnel-vaulted passage to the basilica with 3-bay aisle
arcades with large square piers, plain capitals and round arches
and groin vaults to nave and aisles. At north (liturgical east)
end of nave a round-headed apse (large niche) with pedestal-type
alter. From the antechamber an inclined passage leads up to the
This is the current situation.
More information on the Hall,