I'd be inclined to think that, if London had closed, ZSL would have been "forced" to invest in a long-term plan for Whipsnade-out of necessity rather than choice as the majority of the living collection would have had to have been moved to Bedfordshire in the short term at least.
What plans there were is anyone's guess. IMO, London's closure, though traumatic, would ultimately have been a blessing for Whipsnade. I always have this feeling of always the bridesmaid, never the bride.
I have to disagree with this analysis. Whipsnade has undeniably suffered from neglect, but that neglect ultimately stems from a chronic institutional lack of interest within ZSL in zoos in general, and its own collections in particular. The Society has not been run in such a way to clearly emphasise that the wellbeing and progress of its animal collections are pivotal to all of its fields of activity. Its own Secretary railed against those opposed to the closure of London Zoo in 1991, saying that he would never have agreed to accept the post had he known that there were so many of its Fellows with such an attachment to
"a mere menagerie" . Those were his words; ask Tim May.
if London Zoo had closed in 1991/92 I am quite sure that the effect on ZSL as a whole would have been similar to a battlefield amputation at the time of the Battle of Waterloo. However unavoidable the surgery, the ensuing trauma would have been lethal.
It would not have been possible to move the majority of the animals from London to Whipsnade. The latter lacked - and still does - an Aquarium, a purpose built Reptile House, and purpose built housing for delicate smaller birds and mammals. What would have happened to that world class collection of invertebrates? Quite possibly they might have been moved, but they would have gone off exhibit. And it would have been years before they could have gone on show again. The removal of some ungulates from London to Whipsnade was hard enough - for example, an incipient ZSL group of Sable Antelope was lost because of fatalities due to the lack of suitable housing when the animals were moved.
All this would have cost Whipsnade money that it didn't possess. I vividly remember Doug Richardson saying in 1992 that if one of London's remaining trio of Asiatic Elephants had been sent to Whipsnade, the latter would have gone over budget.
At bottom, though, ZSL would have suffered a cataclysmic blow to its reputation. Dignitaries would have arrived at the Institute for high profile symposia against the backdrop of an abandoned zoo, maybe with various bitterly opposed factions picketing the gates. They would have instantly decided not to touch ZSL with a bargepole. For many years afterwards, and quite possibly still today, getting donations from wealthy institutions and individuals was hamstrung by a reluctance to invest in an organisation seemingly hell-bent on closing its oldest and most familiar brand.
By all means oppose the lack of investment at Whipsnade, and its vast untouched acres. But
please don't fall into the trap of assuming that it would have been better off had London Zoo closed. The goal should be, IMHO, to run the two collections as one site. With an uncompromising attitude towards the pursuit of excellence, the combination could again be world class.