The plot thickens:

It's included in Paddy Berry's "Wexford Ballads", with the following note:

Translated from the Irish of Michael Og O'Longain. Taken from a book of '98 ballads published by the '98 Commemoraton Association - Editor, Patrick Toibin, Enniscorthy, 1938

I know I've seen the Tobin publication at some stage - I may have a copy of it about. If so, I'll check it for further details.

Regards