Interesting photograph. There's a building missing, which is there today but which I thought was original. This looks like it shows the side of the Hall in the background, complete with the old brick wall..which is where the missing building should be if it is.
It's a light-coloured stone building.. the toilets are tucked away in the corner of a small building between it and the Hall. The large tree in your photo could be the one that's in mine which shows the stone building, but not the wall.
Ah, do you mean the one that backs on to the wall and has recently been a bar? That was once the site of a cage for Pumas (they were all over the place of course) and was also used for some of the hybrid Bear cubs.
Oh, I think the building on the left of the photo is that one and not part of the hall. I agree it's an original building and it was the one that had the Elephant House in the middle. The cage I meant was where the canopy is on your picture, i.e. behind this building.