Information taken from "Prehistoric Sites of Breconshire", Monuments in the Landscape, vol 9. Children/Nash, Logaston Pr, 2001
Precise location: unknown, destroyed.
"...George Clinch remarks in 1854 that about 250 yards north-east of a medieval enclosure within St Margaret's Park Wood is a flat, horizontal slab of limestone like the upright of a cromlech"
capstone 9m x 3m, in places more than 1.8m thick
1804 "...stone slab stood wholly free from the ground on certain upright stones, there is still at the west end of the slab, but at a slight distance from it, an upright stone, flat at the top, which may have originally been one of those on which it was supported. It seems probable that these may be the remains of a cromlech".
Grid reference is given for a lime stone slab found on a recent visit, which authors believe may once have been part of the capstone. May represent the south-eastern limit of the Black Mountains Group.