Can't find any documentary evidence on this one, but....
Unless you knew it was there it can only be spotted from the bottom of the permissive footpath that exits RedMoor nature reserve and climbs to meet the Saints Way. Once you start climbing it is hidden by gorse bushes and once on the Saints Way the banks are so high you can see nothing.
It's a big stone!...and just outside the area enclosing Helman Tor. An ancient trackway passes just down slope from it and in the hedge/scrub behind is a large dump of granite that has been cleared from the field. Why was this stone left?
So, I can not prove its origins or find a record of it on maps or any of my books...but it feels right!
I have now had it suggested to me that this stone has been moved from elsewhere in the field...and that they had dowsed the field and found an area with a stone setting in it...
Go look for yourself..and while you are there enjoy the "prehistoric" wildness of Red Moor reserve.
Wonderful place to explore if you want to escape from people! Real mixture of landscapes from flooded pits to mysterious swamps where lichen and ferns add an almost prehistoric feel to the place.
Although much of the wetter bits are covered by boardwalks it is advisable to go in wellys or boots.