Hob wrote:
Nice. Reminds me of this:
http://www.themodernantiquarian.com/site/8819/grange_3.html
There are similarities, but this panel nearby has a more similar design - http://www.megalithomania.com/show/image/8375/Kealduff+Upper.htm (another wet, crap photo!) - centre image there's a blurred group of rings.http://www.themodernantiquarian.com/site/8819/grange_3.html
Note the possible fissure used as a gutter.
The design on the panel I first linked to has lines radiating from a central point with penanular 'mushroom heads' wrapping around the outer ends.