Stronstrey Bank Stone

High up on the moor tops, teetering on the edge of Black Coppice stands Stronstrey Bank Stone with it's carved triangle. Some claim there are two, one sat on top of the other.
I've intended to visit for ages now and finally made it up there just now. There's no clear indication as to what the triangle(s) refer to. Some say they indicate the locations of other sites that were important to peoples who lived here long ago.