Thanks for all that info about the history of the 'Green Mile' Pertinax. It's quite sobering to think of 2 pairs of orangs, 1 pair of gorillas AND chimps all once occupying this small area ...... especially if you say the exterior wasn't as large as it is now.
I also agree that the biggest concern about this area is the lack of natural socialisation for the chimps as opposed to aesthetics of their surroundings (which probably matters more to the visitors). Who cares if paintwork is a bit shabby after all ........ though I still think it's important to give the animals as large a space as possible, with maximum climbing opportunities, space to get away from it all and other forms of enrichment.