The last paragraph of information on Wikipedia mentions a hollowed out stone in the nearby stone dyke which travellers deposit a stone in whilst passing, I have just uploaded a picture of this stone, and strangely it had a couple of polished pebbles in it when i visited.
This beautiful little cairn circle has been seriously damaged by a fire being lit in the central kist, you can see by the photos that the stones have been badly scorched, and it looks like the peat infill repairs from the 1993 fire damage has been dug out. These images are from August 2008, i hope that further damage has not occurred since. I am susprised that this is allowed to take place, considering its close proximity to the road, where are the Dartmoor forest rangers or local farmers when this is happening?