This is Arthur's Chair and the ridge upon which it stands is Stone Arthur. Prominence is negligible, and other than the low outcrop itself, the "summit" is merely the point at which the gradient steepens markedly.
Arthur's Chair is located on a minor hill known as Stone Arthur, where its significance is insignificant. The only distinguishing characteristic of this site is the subtle increase in elevation that signals the point at which the terrain becomes more rugged.