I make this denuded monument to be fractionally across the English border... although, to be honest, lines upon maps mean nothing up here. The Offa's Dyke Long Distance Path runs right past the western flank.
Nevertheless, Coflein have the cairn recorded as:
'A centrally disturbed cairn, 14m by 12m and 1.4m high. (source Os495card; SO22NE13)J.Wiles 03.09.02'