Went on a visit again today at low tide with the GPS.

Got a good fix on the stone and surrounding features.

Map here...

http://www.bristolmountainbikeclub.com/stuff/stones.jpg

The recumbrant stone is at the center of the circle. The black lines towards the top are extensions through the wooden post lines.

If anybody wants the exact grid ref, I'll email you.

Cheers for now,

ike