I've been doing some looking for this song. I first heard it on a recording with Dolores Keane some years ago, and I've always loved it, but thought it more a folk piece, a set piece performed with a backing band.
Most of the posted versions of the text read "...the bonny Bann banks", but Keane clearly sings about the bonny Bann "isles". Other than that, there seems to be only this one version.