When Monkey World had these (I think they had the old ones from Chester) they lived in a clump of Gorse bushes surrounded by a simple electrified fence.. interesting how the designs (and the costs) differ between locations.
Because of escapes at other collections , the background of these rescue animals - bad treatment at the hands of man - and the chance of electrical failure , it was felt that they should take every precaution to prevent escapes . With this Folly Farm being designed for children I can understand it .