Becky,I typed in the attribution to both of those right out of the book And Now the Fields Are Green. I don't have a copy of Maritime Folk Songs yet. Someday, I hope to.
As far as the song being to the tune of Mo Rùin Geal Dìleas, it could have been John O'Donnell's impression. I think I have heard it sung to the Mo Rùin Geal Dìleas tune. IT seems to scan properly. Stretching some places, and slurring others in a few places.
If it doesn't show up in Maritime Folk Songs, it must have been in a different book. Did you try the link to the John O'Donnell's book? There might be a link to his e-mail?
I suppose if I were to try and call Ronnie, he might be able to shed some light on it.
If I do get hold of Ronnie, would there be any specifices you want me to ask him about the song?