George, I know the song was written soon after Waterloo (Joseph Lees and his mate Joshua ?Wood flogged copies to the soldiers). Joshua it was who claimed the credit for a time, but later confessed that it was Joseph's work. He also admitted that they penned many of the so-called variants "to reflect the social and political changes" (but mainly to make more money).
Anyway, enough of the history - it was later 'collected' by Frank Kidson, amongst others, and is sung at folk gatherings to this day.
I put it to you that it is a folk song.