I have some clues about where James spent the last years of his life.
Here’s what I know:
The Theatre Royal in Margate meshes well with my memory of working in a theatre in a seaside town. It’s exactly the right size to be the house I seem to remember, and it was remodeled in 1874 but it was about a hundred years old at the time. That might explain my memory of the smell being of a very old building.
Two things it lacks: a chandelier with red, white, and blue ostrich plumes (though that could easily have been removed) and a proscenium shaped vaguely like a seashell top and bottom (though that may have been a backdrop). Also, I don’t know if opera would have ever been performed there (though if I could place a performance of “Nabucco” or “Die Zauberflote” there between 1874 and the first half of 1877 that would help things a little).
From the outside on Streetview, I got chills. The neighborhood hasn’t changed much in the last 150 years and I was a bit blown away by it. But that’s only a subjective impression.
There’s one problem with Margate: there is no canal. This means either:
A. There was one at one time and it was filled in and built over (there’s a street in Charleston, SC like that) or
B. I was mistaken and the place where James drowned was the Margate Harbour Arm, which incidentally was built as a port for steamships and was already there in 1874.
Also, worth noting: in the early 13th century Margate was one of the Cinq Ports. Count William was the warden of the Cinq Ports.