Reinhard wrote: Borrowed is unlikely as Colquhoun was already broadcast singing it on NZBC in 1969, long before The Lightning Tree.

I think it's now established that Colquhoun is the ultimate source; he did not borrow the tune. The question is whether he originated it.

On that point, I am genuinely torn. I've already talked on this point, somewhere in this thread, about this, but it might bear repeating. The two gems of Colquhoun's Song of a Young Country (both book and recording) are "Wellerman" and "Davy Lowston," neither of which he claimed credit for. I think this is pretty much universally agreed: those are the two songs that are by far the most widely sung.

But no one seems interested in investigating the other songs in Song of a Young Country. They are relevant. Colquhoun's hands are all over that book. He wrote the entire song "Murderers Rock," and he copyrighted eight other tunes in the book. At least four other tunes he "reconstructed."

I don't know how many of you have listened to the Song of a Young Country recording. I've had it for forty years, and listened to it many, many times. And Colquhoun's admitted tunes are not at all memorable. Some of his texts I remember (e.g. "Hang down your head, Dick Burgess" from "Murderers Rock"), but the tunes mostly don't do it for me.

Whereas "Wellerman" clearly has a great tune. If Colquhoun wrote it, why is it so much better than his other melodies?

Of course this isn't proof of anything; there are plenty of One Hit Wonders in the world. But it is truly strange, if Colquhoun made the thing up, that it's so much more interesting than all the tunes he admitted to. And, further, note that he was willing to admit to making up tunes -- so why not this one?