It may have been sloppy writing on my part to infer that Do Lord, Oh Do Lord came from Dusenbury. it doesn't. I have seen her lyrics which Charles Seeger repeats in his recording of London Bridge. I think it appeared either in Ruth Crawford Seeger's interpretation of the song or, even more likely, Peggy's remembering of how her mother sang it. In that case it woud be a true mondegreen. Also (and this is an aside to Q) while I may not personally buy the idea of human sacrifice as inherent in the London Brdge song, it has to be addressed as it is important to many who have sung and written about the song. I link to, in my essay, a fascinating counterpart to London Bridge in German and have found very similar songs from other countries in similar language.
As i write up the edited version, I will try to clarify what is the web of associations floating about the song and what can be traced back to concrete cites and observations. Modern folklorists rarely use modern songs to read back into what was once believed (the whole doctrine of survivals) but put their emphasis on what the song means for those singing it.
As a historian by training, as well as someone who has worked in folklore, I think a song can do both -- have relevance for today while shedding insight into the past -- but you have to procede carefully and make sure the clues do not merely confirm what your own illusions are about the past.
One fascinating article i read was by an educator who asked the kids themselves what they liked or felt about singing London Bridge is Falling Down -- no question the kids like the destructive aspects of it -- don't they always?