I had assumed Saint James Infirmary was a place in New Orleans and got interested in the song when I found out it wasn't.

But here is my question (which has nothing to do with the jazz versions of St James Infirmary): Some posts here note that there was once a Saint James Hospital was a leper hospital on the site of Saint James Palace in London and state that that is the hospital in the original Rake song. But that would mean the original Rake song goes back to the 14-1500s, before St James Palace was built on the hospital site. Is there any evidence any place that the song is that old?

If not, could it be that the scholars who associate the Rake song with that particular hospital are wrong, and that the song refers to another St James Hospital (someone mentioned there was one in Liverpool)?