Wow, this is a goldmine! I have been researching song origins on digitrad for years but I didn't realize how much more valuable this forum would be for my class when I became a participant.

re St James Hospital/Infirmary (name): if it's indeed a common hospital name (for such ailments anyway), more so than St George or St Paul etc, then that would make the link rather weak. Hmm, are hospitals referred to by name in any ballads that clearly do not have "Unfortunate Rake" related themes? For example any hospitals mentioned in war/wounded soldier ballads?

re "OK, what traditional songs about leprosy are there?"
Sir Aldingar comes to mind. Not exactly about leprosy, but a leper is important in the plot.

re distinguishing folk process vs plagiarism:
Perhaps there's a subtlety I'm not seeing. I would think that "plagiarism" is claiming something to be one's own original work that is in fact identical to, or derived from, someone else's work (even if that someone else is anonymous). "Folk process" would seem the applicable term whenever a person credits their source(s).

I suppose the tricky cases are when someone is unconsciously influenced by a source they once heard, and honestly believes to have originated it; vs. genuinely independently writing something that turns out to be very similar to something that was pre-existing; vs. knowingly copying something and lying about it. Not being schooled in law, my first inclination would be that moral culpability of the person for plagiarism should be according to their intentions and actual past exposure to the earlier work (which may not be knowable to others); legal culpability according to their documentable past exposure and/or intentions; and copyright ownership according to the objective similarity of the new work to the pre-existing one (i.e., even if copied accidentally or written independently). Thoughts?

re copyrights: a similar question has bothered me about songs that are now attr. to Albert E Brumley such as I'll Fly Away. Is it the general opinion that he wrote them, or merely transcribed/arranged existing folk spirituals?

on a related note -- I routinely get hit with YouTube copyright infringement claims that block my videos of trad songs because some pop/country singer sang a version once, and now their agents are claiming the copyright. Happily YouTube invariably rules in my favor and quickly releases the video if I send them a scholarly reference to a source more than 100 years old. (But sadly, when someone falsely claims the copyright to someone else's copyrighted song there is no such recourse to protect the true songwriter).