For the elephant house, probably big enough for 6 or 7...not more!
Now that ISIS has caught up i see that Woburn now have 3 male Mhorr gazelle, would they be the remaining males from Twycross, as they are showing having none.
Mhorr gazelle and Somali wild ass, Woburn are moving further and further from your typical safari park, the collection is really coming together.
I do not mind the rarer species being off show or in a Conservation Facility. Actually, I can see the point in a separate rare ungulate breeding compound.
As you observed most "regular" zoo visitors do not bat an eye-lid to a Somali wild ass or Mhorr gazelle, much less their rarity or the importance of conserving and breeding them.
I can understand not mixing very rare & valuable species like Somali Ass or Okapis with other species in shared reserves where they could be injured. However Woburn SP is very much a commercial enterprise so why they have aquired e.g. the asses, which are of no special display value to the visitors who go there, seems a bit of a mystery.
Bringing in more elephants will be difficult, because there are basically no female asian elephants in breeding age availible in europe (unless you import some from asian countries). It seems to me that there is a shortage of older non-breeding females at the moment, too. Same for the african species..
This a good idea just it won`t happen because Twycross is not very interested in breeding its elephants.