I reach the end of this series of posts with failure. I have been unable to find any more information on two donors. This is what Clin Keeling wrote in A Short History of British Reptile Keeping:
First there was one C.R. Walker, F.Z.S., of The Vivarium, West Bromwich, near Birmingham, who during the early days of the war sent, and received on an exchange basis, quite a lot of material to Regent's Park; for example one consignment of his consisted of twenty-five assorted Skinks, Geckos (including the New Zealand species) and Tree Frogs, while during research in another direction I made the fascinating discovery that on 15th October 1913 London's first Soft-shelled Turtles (Trionyx) came from him. As far as we're concerned just who and/or what he was must, pro tem, remain a mystery, although it sounds very much to me as though The Vivarium was a shop that specialised in animals of this kind – in which case it must have been one of the very first in the country and possibly indicative that even at that period there was more demand for them than wenow realise – or it could even have been some kind of reptile display, or both. As things stand, though, we must leave it there in the shadowy land of speculation.