The Duke's Table or picnic site constructed for dining purposes during hunting excursions, is located on the east bank of Nant Trefil. The structure measures overall 4.5m in overall diameter. It consists of a central table of stone blocks measuring 2.5m (east-west) by 2.3m and about 0.4m high. It is surrounded by a circular 'bench' 0.5m - 0.8m wide and 0.3m - 0.4m high, made of coursed slabs and blocks. It is separated from the bench by a gap 0.3m to 0.4m wide. In the north-west quadrant of the bench is an access gap 0.5m wide. Both table and bench are now capped with turf though the edges of the stone features are clearly visible.
About 5m south of the table (at SO11441414) lies a springhead said to have been used as a wine cooler. It shows traces of stone lining, and a grooved slab on which immersed bottles might have rested. Immediately above the spring is a further outlet (dry when seen) that might have been created with the same purpose in mind.
A second table, though slightly smaller and now ruinous, lies about 6 km to the east on Mynydd Llangatwg (NPRN 291946).

David Leighton, RCAHMW, 14 March 2016