I've spent a good part of the evening reading through the numerous threads on this subject and am puzzled by the seeming need to label this as a 'traditional' song.

I accept that there are traditional songs with similar lyrics but the song as sung by the great majority of people today is the one that was written by Padraic Colum.

He appears to have followed in the footsteps of AP Graves and resurrected a traditional theme, making a much more singable song by doing so.