Yes, Gerald Durrell did bring back angwantibo for London Zoo.
The Winter 1948 edition of the ZSL publication “Zoo Life” records that Durrell and Yealland brought back an angwantibo from the British Cameroons for London Zoo; this is listed in the ZSL Annual Report for 1948 as a species new to the collection.
The Winter 1949 edition “Zoo Life” records that Gerald Durrell brought back “another angwantibo” for London Zoo from the British Cameroons.
(And the Spring 1949 edition of this publication features an article on angwantibo written by Gerald Durrell.)
