Whenever I visit this area of the zoo nowadays, it just feels so, well, depressing. It's a perfect reminder of why you should put animals before architecture; back in the day, I remember this house and the outside areas bustling with people, all watching and talking about the amazing elephants and rhinos before them, elephant bathtime especially drawing quite possibly the largest crowds you could get in the zoo. And whilst I never saw them, I imagine the sea lions opposite drew just as estactic crowds.
Of course, the realisation soon came that these enclosures were no longer suitable, and the elephants Dilberta, Layang Layang and Mya left for Whipsnade, the black rhinos Jos and Rosie going soon after (I remember visiting about a week or two after the elephants left and Jos was still there). Nowadays, the area has become very desolate. Inside, it is quiet and never as busy as it was. This impressive building (yes, I think it is) doesn't seem quite right now without such impressive animals: The camels and bearded pigs just don't fit the atmosphere the building seeks to make with the atmosphere, lending it's name to what I use now to term a zoo exhibit that doesn't (in the aesthistic sense) fit the inhabitants, the 'Casson Effect'. Likewise, outside is quite bleak, with the camels and hippos quite a quiet display.
I've seen several ideas here as to how it could work better: Conversion of part of it into a great ape exhibit, a similar sized but more interesting display species to a camel, such as tapir, hippo, gaur or even black rhino, and even a museum of the zoo's history, with model elephants to fill the space of a large presence this house was designed for. But then again, we should all blame Hugh Casson for not thinking out the animal's needs first.