Those who know Whipsnade might JUST possibly wonder at the idea, that of all the large carnivores under the sun, its management seriously contemplates Snow Leopard for probably the densest wood in the park.
I really do try, but this list makes me weep. There was never any long-term plan when the African Lions were installed, ZSL simply wanted to highlight its canivore conservation work in Tanzania. Spotted Hyena would have been more unusual and Hunting Dogs would have had conservation value.
I agree with Pipaluk's and TLD's comments about the Chimps and the Sloth Bears. For my money, I would look to have a pedigree group of Chimps; Edinburgh are slowly grafting one into their existing setup, so it can be done.
Just one final thought. I'd suggest that Whipsnade, well managed, had space for the following large carnivores (my choices!): Cheetah, Clouded, Snow and Amur Leopards, Siberian Tiger, Asiatic Lion, Striped Hyena, European Grey Wolf, Hunting Dog, Dhole, Maned Wolf, and Andean, European Brown, Polar and Sloth Bears.