...(Have you read the whole of the Roxburghe collection? I have)...
No, but if I was to discuss a song on Mudcat, then I would look it up before comparing it with another song.

I didn't compare "While London Sleeps" with anything, because I don't know it. I do know "Streets of London", though, and I don't give much for the chances of its feeble tune ever being reused for other songs in the way that the broadside ballad tunes of 17th century London were.

London has a line of urban tradition that runs from Tudor times to the present day, where the usual rhetoric is melodrama, imaginative abuse and hilarious outbursts of bile. Leon Rosselson is maybe part of it, McTell certainly isn't.