O.k. The thread I was looking for was This one, which I would swear was inaccessible yesterday. And I read too much into it; it quotes Dick Holdstock as saying the song was adapted by Lloyd from a broadside. But the tune still strikes me as very like "Alabama."

By the way, that song is on the DT twice, once HERE, and once THERE. The lyrics are all but identical, and the few differences seem attributable to errors in the second of the two.