Great thread. The reason I checked this thread was because of a comment that kept popping up when I searched for the words on Google, which didn't seem probable. The source of the comment seems to be from Daniel Renbourn's YouTube video of the song:

"DanielRenbourn
July 30, 2007
According to John Stokoe in Songs and Ballads of Northern England, This melody was picked up from a street singer in Scotland in 1821."

The video is at:
http://www.youtube.com/watch?v=eUygekEd3DI
It's interesting, because the singer tells a little story before the song starts about the song being sung in a Scottish kitchen before finding its way to England.

Any ideas?

Cheers,
Andrew