Well, this is certainly getting confusing. As I said earlier, the Fause Foodrage tune that Andy Irvine fitted by accident to Willie o' Winsbury is the tune used by Gordon Bok for Arbutus. Prior to 1971, when Anne Briggs recorded Willie to the tune supplied by Irvine, it seems pretty unlikely that it would have been used by anyone else for a Winsbury variant, or for a song based on it; tunes found in tradition for the Child #100 family bear no resemblance to it.Of course, Paddy Graber doesn't seem to have sung the song before 1974; did he use that tune, or another? We now have two different accounts of its origin, both apparently from Mr. Graber (the only source for this song); I'd guess that further speculation on that front is fairly pointless until somebody can ask him directly, though on the face of it it seems unlikely to be a traditional song as such.
I've made a provisional midi from the Bok recording; heaven knows what the time-signature ought to be (my musical theory is very rudimentary) but it's recognisable enough. Would Stewart confirm whether or not Paddy Graber used the same tune? I'm not at present concerned if it's exactly right or not, just trying to establish a general correspondence.