Did you go to the link, Joe? It's on a page from County Mayo, just like it says in my post. Information about the song is mostly on that page: the letters were found in the attic of Peter Jones' family in America. Don't know more than that, except that he(and his brother, I think) turned the letters into a song. There's pictures of Kilkelly there as well.
Sing Out doesn't say much more about it, just posts the link under "Resources" in the front.
I'll check the tune and words.
Blessings,
Barbara