I have always thought that Bedd Arthur is not a "ritual circle" or sub-rectangular enclosure at all, but the remains of a small portal dolmen. The outline is clearly oval, not circular, and one end of the oval is chopped off -- just like the portal end of a portal dolmen. Pentre Ifan comes to mind. The small stones on the periphery all lean in towards the centre -- as if they had been laid originally onto the flanks of a mound (which has now gone). Was there originally a passage grave in the middle? Should there be a cromlech there? Maybe it's collapsed and buried under the turf -- I don't know of any proper excavations. Or maybe the monoliths used for the chamber have simply been taken away by local farmers? We know they used this area in the 1700's and 1800's as a quarry for gateposts and lintels etc.
Something is not right. This message is just to keep things from messing up down the road