Gaur and Onager apart, Whipsnade appears uninterested in "hoofstock" these days. (That's a term I dislike, but it does serve to show that hippos and rhinos aren't being discussed).
Congo Buffalo, Nilgai, Nyala, and Arabian Oryx have all been allowed to go, and Hog Deer and Blackbuck look set to follow. Add to that Chilean Pudu and Arabian Gazelle leaving London - where at the moment the only deer or antelope on display are domestic Reindeer - and it portrays a pretty dismal picture.
What is irritating is that species have been brought into the UK in the last 15-20 years ago that hadn't been on display at the start of that period. Kiang, Vietnamese Sika, Bactrian, White-lipped, Brow-antlered, Prince Alfred's/Philippine Spotted and Persian Fallow Deer, Banteng, Lesser Kudu, White-tailed Gnu/Black Wildebeest, Blesbok, Mhorr Gazelle, Kirk's Dik-dik, Mishmi Takin, Bharal, Japanese Serow, and Grey Goral have all been imported in that time.
Surely some could have found their way to either site ? In particular, it's hard not to feel that the Central Asian taxa would have done rather better at Whipsnade than some of the African species held there - the Roan Antelope have never done as well as they did at London in the 1980s, for example.
This isn't the place to re-hash Damian Aspinall's diatribe, but that did show that it it is possible for ZSL to be attacked, however erroneously, as being uninterested in breeding endangered species. A more adventurous species selection policy would go some way towards dispelling such comments.