Just indexing some soundfiles and have come across an Irish version of Barbara Allen entitled 'Barbrellen' from Connemara singer, Treasa Ni Cheannabainn, from Connemara.
It begins:

Oh Christman comes but once a year
When the leaves they were all falling
It being the time when a young man
Fell in love with Barbry Ellen

The singer's repertoire would be basically Irish-language Seán Nós, but this may well have been acquired from the revival - or who knows, Peter Buchan may have taken a day-trip to Ireland sometime!!
It's from an album entitled Musique Du Monde (Irlande - L'Art Du Sean Nos) (no notes)
Any idea where it might have come from
Jim Carroll