London Zoo should have been put down by now. Hamstrung by its past, weakened by under-investment, wounded by amateur management, a metaphor for modern Britain, it was declared extinct on 17 June 1992, when its ruling council discovered that even a ritual last-minute bail-out was to be denied.

'Our view is that people in the 1990s believe that confining animals in a 37-acre site in Regent's Park is not appropriate,' a Department of National Heritage spokesman said at the time, applying the final dose to the syringe. 'There will be no more money from the Government for Regent's Park.'

Last month this same zoo announced its first working profit in 17 years. Instead of its usual autumnal crisis, the corner of central London that Sir Stamford Raffles coralled in 1826 for the purposes of imprisoning his collection of wild animals can look forward to its winter hibernation with something approaching optimism.

Taking his daily stroll round his squawking, grunting, smelly domain earlier this week, Dr Jo Gipps, the curator appointed in the midst of crisis in 1992, explained that three incidents had saved the zoo. First, the Emir of Kuwait, as a thank-you for his country being rescued from the Iraqis, gave it pounds 1m. Then the publicity generated by the closure announcement resulted in a huge increase in gate receipts.

'Those two kept us open last winter, and if you stay open over the winter, you might as well keep going over the summer, because that is when you make money. But the real turning point for me came when poor Ben Silcock climbed into here last New Year's Eve,' he said, stopping outside the Lion House, where a large-maned beast was sitting smugly in the autumnal sunshine. 'We were at rock bottom, our public relations was universally bad. But because we acted promptly and he survived and the lion survived, for the first time in ages, nobody blamed us. Somehow it seemed to me a sign that we were going to be all right. That, by the way, is the lion that got him.'

Instead of overseeing the zoo's demise as he had been appointed to do, Dr Gipps found himself midwifing its rebirth. Given the opportunity that the lion incident and some tight cost control gave him, he was not content simply to let the place lurch on as it had for nearly 20 years. Three million people visited the zoo in 1956; two million in 1973. Now Dr Gipps budgets for 850,000. There are many more rival attractions these days and, for thrills, a giant panda simply does not compete with Alien Wars at the Trocadero Centre.

'When we brought the panda back, we made quite a fuss, put up crash barriers and got ready for big gates,' said Dr Gipps, looking at the creature lying comatose in a corner of its enclosure. 'And nobody came. Which was no surprise, as that's about as exciting as a panda ever gets.'

Worse for the zoo's finances, many of today's children, far more ecologically aware than their parents, find the sight of a giant panda in a concrete cell, its walls painted in bamboo patterns, offensive. The modern orthodoxy is that efforts should be concentrated on preserving animals in the wild. The concept of the urban menagerie is deemed to be spent.

But Dr Gipps knew that in Europe Berlin Zoo played host to two million visitors a year; that in America the Bronx, Central Park and Cincinnati zoos had brilliantly reinvented themselves, liberating both animals and visitors with astonishing new buildings and interactive displays. He saw the opportunity to change an entire philosophy, to find a new and appropriate role for London Zoo.

'It is hard not to be disparaging about the previous management, but their basic problem was that nobody realised conservation can sell tickets,' Dr Gipps says. 'Everything was wrong with the way we presented ourselves. London Zoo has always done far more in terms of conservation than it has taken credit for. Visitors could walk round largely unaware that we were doing anything other than keeping animals. Well, they won't be able to do that any more.'

The first action in the Gipps plan was to produce an advertising campaign that aggressively promulgated the zoo's work with captive breeding of endangered species. 'Without zoos, you might just as well tell these animals to get stuffed,' ran the copy line. Every leaflet and poster was flagged 'London Zoo - Conservation in Action.' The signs on enclosures, which had always been, according to Dr Gipps, 'name, rank and number stuff', blossomed into short essays on conservation.

However vigorously Dr Gipps sells the zoo's behind-the-scenes work, though, the public are still dismayed by the sight of elephants in concrete enclosures, of turtles in tanks that a goldfish might consider cramped, of apes acting bored behind bars. In American zoos visitors can enjoy watching animals cavorting in a good approximation of their natural habitat.

London Zoo will not be going down this route. After lengthy consultation with the staff, Dr Gipps produced a business plan in February that centred on a pounds 21m, 10-year reconstruction programme. The aquarium is to be redesigned, the derelict Parrot House will become Invertebrate World; the bulldozers move into the concrete swathe of the children's zoo next week.

'We will be fulfilling our mission in every way,' said Dr Gipps. 'These new places will be involved in vital conservation work and it will be thrilling for visitors.' But despite such fancy face-lifts, in the end most of the old zoo will remain as we now know it.

'We're stuck with this thing, for instance,' Dr Gipps said, slapping the white concrete side of Lubetkin's Modernist dream of a penguin pool, in which a couple of occupants were engaged in frantic captive breeding. 'It's listed up to its eyeballs. If you were going to build a penguin house now you just wouldn't come up with this.'

And it is not simply that Dr Gipps is constrained by his architectural surroundings in a way that no American curator would be. He believes the US solution to urban zoos, to theme-park them up with ersatz rainforests and walk-through aquaria, is not so much directed at the animals' welfare as at salving the visitor's conscience.

'Even in our limited space one could build fancy hi-tech displays where customers are immersed in a fake version of the wild environment,' he said. 'But they may not be the best use of your resources for animal conservation.' Instead he cites his new gorilla enclosure as the way forward. Built in the Mappin Terraces, derelict for eight years, it will have lots of space for the animals. It will not, though, be made to look as though they are patrolling a mountainside in Zaire, with David Attenborough about to pop out of the undergrowth.

'I don't think we could or should try to kid the customer that this is a bit of Africa transported to a corner of Regent's Park,' Dr Gipps says. 'It would be fearfully expensive and in the end unnecessary for the animals' wellbeing.'

At the moment, the Gipps plan is so much fancy coloured drawing. It might go no further than the wall of his office if money, and large amounts of it, is not forthcoming. The zoo cannot finance ambitious improvements solely through gate receipts. The Government has said it cannot help. The zoo needs more benefactors like the doctor who provided a million to spruce up the children's zoo. And until they step forward, while you can see tomorrow's zoo today in Cincinnati, San Diego or Berlin, in London you will be lucky to see it in the next century. Now, isn't that a familiar story?

(Photographs omitted)