Also wheelchair access, for years they had signs apologising for the first few steps up to the bottom level, with plans for a ramp etc, which would never be possible further up. It would be impressive to see animals using the upper area, the public would still be able to see them from the current viewing level. As london is no stranger to hotwire, I'm sure the area could be secured for the langurs to have access to, but then I've heard stories of Markhor escaping down the back so I guess it's a potential PR disaster and will probably stay as a rather impressive backdrop for the Sloth bears.