The music hall/theatre I’m looking for had a proscenium that is similar in shape and color scheme to the organ seen here. While not exactly the same, they do share a basic shape (rounded and undulating) and color scheme (gloss white with gold trim).
So far my searches have turned up nothing, but I do know that the surviving music halls and theatres in England are only a small fraction of what would have existed prior to 1914. Many of them sadly vanished without a trace, with no photos, drawings, or descriptions surviving because nobody in the early 20th century thought they would be worth remembering. By the end of WWII, the music hall had all but died out and it’s only been in the last 30 years or so that many of them have been restored to their former glory.
It’s sad to think that there’s a distinct possibility that I’ll never find this building even if it did exist.