The Lloyd tune (which I know from MacColl's book, I assume he didn't mess with it) is exactly "The Banks of the Devon", not just similar to it. It's not a tune that changed much.

Broadside writers didn't set their work to tunes that were only available in undocumented oral tradition. The fact that Wilson didn't even bother to print the name of the tune suggests he had a locally familiar one in mind. And "Banks of the Devon" was certainly that.