I am embarrased to admit I have been to London Zoo two years in a row and have never step foot inside this aviary. (I will make a point of it whenever I make it back across the pond as the Brits say).
I'm not sure it's worth the bother, except to say that you've done it. It has never really worked. The sharp angles preclude keeping anything large, and the lack of indoor heating makes keeping smaller delicate birds impractical. In Tucson it would probably be quite an interesting exhibit, but in London it's had 47 years to demonstrate the fact that, sadly, it isn't fit for purpose.
