Gosh.....Ive NEVER heard of a zoo at St Asaph before reading this thread! (excuse me joining in so late!!) My sister lives very near what is now the Tweedmil shopping outlet....its certainly not common knowledge there was ever a zoo there! the best i could find locally is possibly a travelling collection used to use the site as its base in the winter. I'd love to hear more about this!
Clinton Keeling wrote a chapter on it in one of his "Where the..." books, and there is a page on it in "The Penguin Guide to British Zoos" (1970). In the latter Geoffrey Schomberg's final sentence reads "The combination of animals and scenery is pleasant, but do not expect to be set on fire by the collection". It did house "Hannibal" the Asiatic Elephant for a while of course - he later was at Flamingo Park, APP did move a lot of things around. He was at Flamingo by 1970 and Geoffrey Schomberg says St Asaph had a "baby Elephant". In the guidebook described by Clin Keeling "Hannibal" was called a "baby", but that would have been a few years earlier (maybe circa 1965 which is the opening date given in the Penguin book, of course it was called Llannerch Deer Park then).