Hi Adrian, what a superb photo. I hope you don't mind, but I've annotated it to show three locations that I managed to get "present day" photos of yesterday.
Here I've mark three distinct roof areas:-
#1. This is the dome just inside the main entrance, part of it is boarded over now, but its features can be clearly seen here.
#2. This is what is called "The Snooker Room". Although the present day image doesn't show clearly the "windows" as seen in Adrian's pic, you can just make out the outline of the boarded up framework below the "lowered" central ceiling.
#3. This is the Main Hall. Its orientation takes a bit of getting your head around, as it's not obvious from the inside that this wonderful grand hall runs
across the back of the building.
I will try and get more into a gallery in the next couple of days.