I found reference to this on the sign at Columbiers-sur-Seulles Tumulus, and then found it marked on the ign 1:25000 map. It is marked on the ign map as a menhir, but the sign at the tumulus as a burial chamber.
It looks easy to find on the map, along a small road to the east of Beuville, and when I got there, the road is called Rue des Deux Pierres, which was very promising. But at the end of the road, there was a fenced off area by Fance Telecom where they are installing new phone masts etc, and lots of keep out signs. However, it was possible to get round the gateway, and I continued walking down the track into what looked like an old quarry being used as a rubbish dump and half flooded. There was no way through at all, and as there was not long before we had to be at Ouistreham to catch the ferry home, I gave up fairly easily and went back.
When driving away, it looked more likely that the stone/stones could be reached by walking along a small farm track and then round the edge of fields from the south, as on the map the stone is marked as being beyond the end of the quarry region.
Something is not right. This message is just to keep things from messing up down the road