It's an Irish song made famous by the Dubliners.
Nice when someone chances along and drops us the definitive dope, complete with provenance and references, isn't it? Cheers, The Knowledge; I'll stick it in me songbook alongside The Grey Funnel Line, Geordie, John Barleycorn, Santa Lucia, the Marseillaise and the Horst Wessel Lied as a fine example of those grand ould Irish songs.