E G Boulenger's book on the New York Aquarium is in dean's bibliography; I have a copy of his, 'The Aquarium Book', first published 1925 and reprinted two years later. This is about the London Zoo aquarium and although not written as a history, it has effectively become a detailed snapshot view of the aquarium, with a twenty page introduction before recording what was on display. He mentions Westminster and Crystal palace aquariums but only briefly. There are cigarette card sets too that give an indication of the displays. More recent history than Westminster but interesting none the less.