"what exactly are the consequences of this bloke ever having come across an American version of the Unfortunate Rake"

Hi Al,
Perhaps this comment is a timely reminder that when a bunch of specialists get to discussing fine details, then the overall picture may be obscured. I still like to think of Mudcat as a resource for the curious, so, to briefly answer your question:

It's been accepted wisdom for many years in the folk revival that an English song called 'The Unfortunate Rake' was the precursor of 'St James Infirmary' partly because of the funeral arrangements with six pall bearers etc, but also because there were thought to be versions of the English song set in 'St James' Hospital'.

More recently, some researchers like Karen here have disputed this, on the grounds that no English versions of the song actually mention 'St James Hospital', a line that seems to been interpolated into the song by Bert Lloyd, from an Appalachian version.

There is a single Irish version (Tom Lenihan's) that does include the 'St James' line. But this was collected after the Louis Armstrong recording had become a hit, so the possibility arises that 'St James' went into the Irish version from America, not the other way round. There are plenty of examples of traditional singers being influenced by commercial recordings, but in this case there are strong reasons (as Jim and I have explained) to believe otherwise.

I don't know whether or not this will convince you that it's a matter of great import when the rest of the world is falling apart around our ears, but to those of us interested in this kind of stuff it certainly is.

"Not knowing a lot about music. I never really understood about how the Streets of Laredo related in any way to St James's Infirmary."

In many ways you'd regard them as different songs, but the basic plot is that someone has died and a funeral is being arranged. Then compare:

Get six jolly cowboys to carry my coffin,
Get six pretty maidens to bear up my pall

with:

Get six gamblers to carry my coffin
Six chorus girls to sing me a song

Too close to be coincidental, I would think. Then you have less well-known versions of the cowboy song that include the line: 'As I passed by Tom Sherman's bar room', which chimes with 'old Joe's bar-room'.

Just because it's a great recording, here's Tom Sherman's bar-room.

And, again because it's a wonderful performance that deserves its own blue clicky, here's Iron Head Baker's version, which includes verses that look like they belong to English, cowboy and jazz versions.

It's not easy to determine the exact sequence of events, but the three songs are very clearly entangled.