i got it off Urban75, but it came from somewhere else and didnt say exactly where.
So all I know is whats put there, it's near Maesteg, and is a barrow apparently, but that's me lot.
As others have said, make a propoer study of the place & then build the buggers! I think it's a pretty reasonable way of honouring ancestors really green energy, certainly no worse than abunch of hippies wandring round going, oooohh. :)