Many a true word said in jest! For many years I took sixth form students to Pembroke and part of the weeks entertainment was a river study on the Preseli Mts. where the bluestones for Stonehenge come from. I regularly joked that Stonehenge was originally sited there and the English whilst on holiday rather took a fancy to it and nicked it! Apparently this is now an accepted theory (well the bit about it being originally constructed there.!! Guardian article