@Ned - I'm not certain, but I did hear from a volunteer that the property has been owned by Bristol Zoo for generations and it was previously used for quarantine of new species intended for the main city zoo.
I've just noticed the typo in my post, I think I was writing I wonder what this enclosure was built for? not sure how it ended up as address though?
Yes the estate was owned by the White family (aircraft manufacturers) until the 1960s and some features of the park are from the original landscaping such as the ponds in the woods opposite the giraffe house. Bristol Zoo acquired the estate in the 60s, this pond in the photo and adjoining stable must have been built to accommodate some animal or other. It would be interesting to know what.
Incidental, the structure that covers the play equipment at the back of the visitor information building once held giraffes. There was also another giraffe house that stood on the site of the current one.