Many thanks to thereddragon for this ancient document.
Such documents, hard to come by, are indispensable to retrace the reception of megaliths in the modern times ; the legends attached to such stones are probably as interesting and valuable as the reality.
In this particular case, recent academic studies are, alas, more sobering and consider the stone as a "natural" stone : http://www.megalithe.be/sites/default/files/Dolmen_de_Solwaster.pdf
All the same, Merci Red Dragon !
Something is not right. This message is just to keep things from messing up down the road