It really should be set to music--I wonder if it has...

From the "sacred-texts" link:
The legend is now firmly established at Bedd Gellert, There is said to be an ancient air, "Bedd Gelert," " as sung by the Ancient Britons"; it is given in a pamphlet published at Carnarvon in the "fifties," entitled Gellert's Grave; or, Llewellyn's Rashness: a Ballad, by the Hon. W R. Spencer, to which is added that ancient Welsh air, "Bedd Gelert," as sung by the Ancient Britons. The air is from R. Roberts' "Collection of Welsh Airs," but what connection it has with the legend I have been unable to ascertain. This is probably another case of adapting one tradition to another.

There you are WordWanderer...a-googlin' now to go! ...

The Only WO'N!