Brian - I suspect Martin Simpson picked up the New England strain of the song when he lived in the US for many years. I guess he's combined the American version with the Irish tune? It's amazing how often these melodies are repurposed and reused, often with a differing tempo and chord progression which makes them almost unrecognizable. For instance, it recently blew my mind that the tune that Andy Irvine used for "There's Sure To Be a Row" on The Gathering album is the exact same melody as Dives and Lazarus, only with a jaunty tempo and a major feel instead of minor. Just goes to show how versatile these old tunes are.