....the small mammal house with Quokka, ground or possibly even spotted Cuscus, and North American porcupines, other marsupials I can't remember, quite possibly tree kangaroos. Twycross and blackpool seemed to aqcuire an amazing range of unusual marsupials at one point together, which gradually died out over the decades. The ground cuscus and the odd wallaroo seem to be the remnants of this.
in the book "Chimps With Everything: the story of Twycross Zoo" by Molly Badham (1979) it says (on page 130) that they were contacted by a woman called Anne Ulrich who had been doing work in New Guinea and had amassed a large collection of wildlife which she wanted to bring out of the country and donate to Twycross (I guess things like that were easier in those days!!). Amongst the animals were three spotted cuscus and fourteen tree kangaroos (apparently of various species?), as well as wallabies (unspecified) and a fruit bat. The quarantine was divided between Twycross and Blackpool, so presumably animals went to both zoos once quarantine was over.