After several enquiries with local people, including Patrick Will, it seems that this stone was moved from Shethin Stone Circle during the late 1800s. Fairly obviously it has been used as a gatepost but it hasn't been damaged. Standing at 4 feet tall it still is an impressive piece of granite.
Can be found at the northern entrance to Shethin farm. Both neighbours spoke and asked loads of questions about the area. Thankfully it was me they spoke to, if Patrick had been there he'd still be there and the locals would have been much richer in the knowledge of their local area. The man is a genius!