Of all the now-closed UK animal collections, the two that I most regret closing are Kilverstone (with its great collection of neotropical mammals) and the RSCC (with its fascinating collection of rarely seen species).
Listed below, are some thirty plus animal collections in the UK that I visited and which have subsequently closed; most, but not all, of these are featured on the Bartlett Society list. I suspect my list should probably include a few other minor closed collections that I have visited and which have temporarily slipped my mind.
Basildon Zoo
Blackpool Tower Aquarium
Blean Bird Park
Bournemouth Aquarium (a different place to the current Bournemouth Oceanarium)
Brixham Aquarium
Cricket St. Thomas
Crystal Palace Children’s Zoo
Gatwick Zoo
Glasgow Zoo
Ilfracombe Zoo
Kilverstone
Leeds Castle Aviary
London Butterfly House (Syon Park)
Margate Aquarium & Mini Zoo (Cliftonville Lido)
Margate Aquarium (Palm Bay)
Margate Dolphinarium (Queen’s Hotel)
Margate Zoo (Dreamland)
Mole Hall
Merley Bird Gardens
Olney Flamingo Gardens
Peakirk (Branch of Wildfowl Trust)
Poole Aquarium & Serpentarium
Poole Park Zoo
Ramsgate Zoo (on the seafront)
Rare Species Conservation Centre (RSCC)
Robin Hill (Isle of Wight)
Rode Tropical Bird Gardens
St. Catherine's Island Zoo (Tenby)
Southampton Zoo
Southend Zoo (in Peter Pan’s Playground on Southend Seafront)
Southend Aquarium (near entrance to pier; not to be confused with the current Southend Aquarium)
Stagsden Bird Gardens
Tropical Wings (currently still open but closure is imminent)
Windsor Safari Park