You must mean Ogof Y Pebyll Bone Cave (SS951807):
http://uk.multimap.com/map/browse.cgi?grid=SS951807&scale=25,000
Looks like it's on private land.
K x
I think that's the one.
Don't worry about the land being private - a mate of mine asked the old lady who owns the land - she's not fussed so long as you show some respect.
have you even been there? where did you get the name from? I've never heard it called that before.
rinky