:o)
Chris
Your're right it is Fernworthy, but it comes up under Ireland - Castleruddery stone circle, and Rupert Soskins mentions Fernworthy..
http://www.themodernantiquarian.com/site/1257/castleruddery.html
The slots and drilled holes on this site are the ones he was looking at, one stone seemed to have been drilled to split, (equally spaced drilling holes) but the slotted ones seemed different....