Mr Gill's great passion is conservation. And it's a gospel he preaches with missionary zeal at every possible opportunity. He talks to the crowds of visitors who gather every day to watch the animals being fed, or even to help with feeding some of them.
"While they're feeding the monkeys, we hit them with the destruction of the rainforests, " he says. He never misses a chance to urge people to boycott hardwood furniture. "While we pay big money for woods such as mahogany and teak, Brazil will continue to supply them," he says. "If we buy these woods we are the biggest killers of wild animals in the world. We are taking their habitat away."
For him, conservation is not simply about saving the world's rare and endangered species, it's about saving their habitats as well. "You have to save the ants to save the tigers," he says. "Everything depends on everything else. Without the ants the tiger dies."
An estimated 400 Sumatran and 300 Amur tigers remain in the wild. Until last year, about 90 tigers a year were killed in north-east Russia. Last year 15 were poached, which is still 15 too many, but it does mean the surveillance and protection scheme is beginning to work.
The wild animal park is the only zoo in Britain to have Sumatran as well as Amur tigers. And unlike any other zoo, here they have to search or climb for their food as they would in the wild. "Children and adults alike gaze open-mouthed at the sight of a 30-stone Amur tiger shinning up a 20ft pole to reach his meal," says Mr Gill. He goes on to stress that only about 5,000 tigers may remain in the wild today - and there could be as few as 3,500.
"The situation is bleak," he says, "and it will get worse. We must face reality now. There is no longer a choice between animals in the wild or in captivity. For some, like the Sumatran tiger, it is no longer a question of what might be preferable. The zoo represents the last hope of survival."
The park has more than 120 species of rare and endangered animals, many of which roam free. You can have ring-tailed lemurs cavorting around your feet, stroke kangaroos and wallabies - if they consent to stay still long enough - and hand-feed exotic Asian deer.
The park's new #163;75,000 education centre, which opened earlier this year, should go a long way towards encouraging children to ask questions about conservation. Many thousands of children have already visited, an indication that Mr Gill is already succeeding in his aim of creating closer ties with schools.
He doesn't want the park to be "regarded as having novelty value, but to offer a long-term relationship with the children. They can grow with the zoo." He adds: "They can study life, growth and movement in a developing sense, as they themselves develop." Four local teachers are helping produce a zoo manual for teachers so when they visit the park with their class they already know what it has to offer and how best it can fit into the curriculum.
They are also devising trails with variously coloured discs, appropriate to the subject to be studied. The park's education officer and another member of staff will be on hand to talk to children and answer questions. The education service is geared to youngsters from infants to upper primary classes as well as special needs children.
Mr Gill is, of course, aware that education isn't only for children. As he points out, 70 per cent of the park's 100,000 visitors last year were adults. "If we don't reach the adults now, by the time today's children have grown up the endangered species will be gone," he says.
A great deal of effort goes into raising money, not only for the animals now at the park, but to help conservation and education abroad. There's a non-stop money-raising effort to help save the tigers of Sumatra and the Amur tigers of north-east Russia. The money pays for protection from poachers - ex-army soldiers in northern Russia are now employed to protect the Amurs - and for equipment and research into their habitats.
"I used to be a bit shy about asking for money," Mr Gill says. "But not any more - the need is too desperate." And "desperate" is, you realise, the only word to describe the situation when he tells you the Sumatran and Amur tigers probably have only about three years left in the wild.
In the past eight months the park has sent #163;17,000 to Sumatra to protect the tigers' habitat and food. Not surprisingly, it is recognised as one of Europe's leading conservation zoos. "We don't just talk about conservation," says David. "We do it."
A teaching pack will be available in November and free copies will be sent out to schools. Teachers who do not receive a copy can get one by applying to the South Lakes Wild Animal Park, Broughton Road, Dalton-in-Furness, Cumbria.
The South Lakes Wild Animal Park is one of the major partners in the Global Tiger Patrol, part of the Tusk Force, based at London Zoo. Those who wish to support the international battle to save tigers can send donations to: 21st Century Tiger, co London Zoo, Regent's Park, London NW1