There aren't any details about this stone on its Coflein record. Maybe this unpleasant / unlikely story is about it. (Maybe it's about the Gwern Einion stone but that, at 1m, would hardly seem to be towering anywhere.) Or maybe you know the stone it refers to. You'd hope it'd be safe if it was in a wall.
In the parish of Llanfair, on a small farm called Gwern Einion, is [a] cromlech, of larger proportions than those already mentioned [...]
Not far from this spot is a remarkably fine maenhir, built in the middle of a high wall; over which it towers, and presents a conspicuous mark against the setting sun. This stone, local authorities say, was originally dedicated to the sun; and when it was judged expedient to burn a human victim in honour of that luminary, the unfortunate sufferer was secured by iron chains to the stone. The lower part of the stone is now embedded in the wall, so it is not easy to make out the traces of the fire; which otherwise would, no doubt, be discovered, and believed by the peasants of the district. There is little doubt that many other monuments of the same character have once existed in this district, as here and there fragments of them may be found in the stone walls which divide the enclosures.
From 'Cromlechs in North Wales' by E L Barnwell, in Archaeologia Cambrensis Vol. 15 (1869).