mav, here's a comprehensive look at the legend and the Celtic myths behind it. You have to scroll down to XXI. Beth Gellert:

http://www.sacred-texts.com/neu/celt/cft/cft28.htm

Also found this curious tidbit in the text:
or in Bingley's Tour in Wales (1800).

Bingley?...your namesake? Or have you been around a lot longer than you've been letting on to us?

The Only WO'N!