I've not managed to visit this site yet- the timing of public transport to the area is a little scarey!
The stone is triangular (like a shark fin) and has a hole near the base. From pictures I have seen the hole is elliptical not round.
It has some of the usual legends associated with it- it dances round the field between midnight and dawn, will follow people and will go down to the river to drink. It also guards a treasure which can be seen through the hole while the stone is in motion.
I think a wimble is a stone mason's boring tool.
Something is not right. This message is just to keep things from messing up down the road