Unmarked on the OS map, even Coflein have a “?” after its standing stone attribution. I like it very much, in its field of lambs and with the ubiquitous great views of the mountains. It certainly seems all of a piece with the other stones of the area, both in composition and shape. Deserving of attention anyway.
Visited 11th May 2003: This was the last site I visited on my way back from Oxford. I found it from memory, having seen it listed on CARN. Thought to be a standing stone, the Hindwell Stone stands 300 metres (west north west) of the Four Stones. Although it's a lot smaller than the stones in it's neighbouring site, the type of stone and shape is similar.
I got more excited about this little chap than I did at the Four Stones. The surrounding hills, and Old Radnor were easy to see, and there are no nearby houses (unlike the Fours Stones). The ploughed field had a slightly Zen quality, with the stone sat on a small island of uncultivated soil. I really enjoyed visiting this obscure little megalith!