Another picture of the two stones viewed side on, well illustrates how thin they are. Looking E, now the flat faces incline you to look across them. It strikes me that if the nearer stone were truly vertical its left face and the farther stones right face would form a crack when viewed from this point which would quite accurately locate a point on the horizon, where did I put that theodolite....

The Cwm Garw pair of standing stones, 
looking E

There are several arthurian references in the landscape around these mysterious hills. In the valley on the boundary of the Parish of Meline and Mynachlog Ddu (SN 102322) are cerrig Marchogion or The Stones of Arthur's Knights standing now as boundary stones. Farther along the range is the peculiar stone circle of Bedd Arthur, or Arthur's Grave. Below that in the valley is the huge (probably natural) Carn Arthur, with a large rocking stone.

In "The Ancient Stones of Wales" by Chris Barber and John Godfrey Williams it says, "The presence of so many Authurian sites so close to Gors Fawr must be significant. Those that believe that Arthur was a 5th-century king would expect to find plenty of legendary lore linking these ancient stone sites with their Arthurian names, but there seem to be no records of such tales. Alternatively, Arthur may be considered as Arth Fawr, The Great bear and a representation of the Polar Force. There is in fact an important SCEMB line passing through the Gors Fawr Stone Circle. It starts at the Warrior Stone (SN 138330) and goes south through Gors Fawr Stone Circle (SN 135295) to a large prehistoric earthwork on the side of the railway at Clynderwen on the other side of the main road from the railway station and church, which is marked as Earthwork on the One Inch Ordnance Survey map (SN 123190)."