There's also a small African savannah species in the African aviary I believe.
http://static.zsl.org/files/zsl-london-and-whipsnade-zoos-animal-inventory-311206-353.pdf
This lists it as a Von Der Decken's. That sounds about right.
Also one Ground Hornbill(blue pouch- is red or blue skin a sex or subspecies difference?) in Monkey enclosure- mixed exhibit.
Red and blue is a different subspecies, one is the northern and one is the southern...
Abyssinian Ground-hornbill Bucorvus abyssinicus (also known as Northern Ground-hornbill) is the one with the blue skin and the Southern Ground-hornbill Bucorvus leadbeateri is the one with the red skin.
Did you go to whipsnade?
agreed. which primate species is mixed witht he ground hornbills? does th butterfly area still exist? and are red pandas back in regents park yet?