An isolated pinnacle is shown (with a water depths over of 3 1/2 fathoms) some 750m to the west of Sheep Island on an historic chart. Described as '? several patches off the southwest side of Sheep island, the shoalest, named Sheep rock of 3 1/3 fathoms..' in Sailing Directions dating to 1884.

Sources include:
Admiralty; 1884, Sailing Directions for the Bristol Channel, 4th Ed, pg55, 58
Historic Admiralty Chart 2393_A6 RCAHMW digital collections sourced from the UK Hydrographic Office and first published in 1856

Maritime Officer, RCAHMW, August 2014.