By Victoria Bartlett
BBC Hampshire & Isle of Wight
John hand-reared a tiger cub called Tig until it was 18 months old
John Knowles founded Marwell Zoological Park in 1972 as one of the first in Europe to focus on animal conservation.
Within a few years it became an important breeding centre for several endangered species.
As a child John loved to visit zoos, kept stick insects and had his heart set on becoming an elephant keeper.
There was no doubt in his mind that he would work with animals - it was just a matter of how he would get there.
In the real world
FACTS ABOUT MARWELL
The scimitar-horned oryx was one of the first species kept at Marwell and more than 200 calves have been born and reared there since 1972.
Marwell Hall is a Grade I listed building and was once the residence of Sir Henry Seymour - brother of Jane Seymour, Henry VIII's third wife
The Marwell Zimbabwe Trust was established in 1997 as a non-profit making wildlife conservation and research organisation.
Marwell helps to protect Amur Leopards - a census carried out in February 2000 found only 27 of them left in the wild.
John said: "I was a disaster at school - I could never stick around long enough to pass exams - so I couldn't go into zoology or veterinary science. I went into farming because that was my only option.
It was his work in poultry farming that ultimately took him closer to animal conservation: "My job took me around the world and I saw first hand the real 'human versus animal' struggle.
"I went to the local zoo in Sri Lanka and was shown a baby elephant with gunshot wounds, whose mother had been killed. The next day I met the man who had killed the elephant, and because he could tell I disapproved of what he'd done he showed me where the animal had destroyed his sugar cane fields that would have fed his family for a year.
"He said to me 'you can afford to care about the elephant - I can't.' That was a big step in my philosophical development.
"In the early days of conservation people believed that if we took away the guns and the nets it would solve the problem - but I learnt that unless you deal with the human situation, killing of animals will never go away."
John, now 80-years-old, describes how "an extraordinary series of chance events" led him to gaining the knowledge and confidence to start Marwell.
By coincidence he met the owner of the two Boston zoos, who became a good friend and took John to meet directors of other zoos.
Catskill Game Farm in upstate New York made a big impression on John - he went there any spare weekend he had just to help out.
"Every animal is impressive to me but my favourite is the Okapi" says John
John learnt a lot of commercial tricks through Catskill's owner, Roland Lindmann, but there was also a defining moment for John:
"I once mucked out the Przewalskis horses and I just fell in love with those guys - that gave me the impetus to finally start my own place.
"I wanted Marwell to be a combination of Whipsnade and Catskill. My favourite zoo at the time was Whipsnade but people often complained it was so big that they couldn't see animals - and people won't pay if they can't see any animals!"
Funding the dream
The company John was involved with went public in 1968, at which point he decided to sell his shares to fund a zoo.
John said: "I was convinced then, and I still am today, that many animals have no future. Therefore it was vital to create a zoo that would keep species going.
"I always wanted to live in the south of England and I needed somewhere that had good soil that was fairly free-draining so that we could have a preponderance of hoofed animals outside for large parts of the year.
"Plus it had to be a location that would have enough potential visitors to make it a viable proposition. All this pointed to Hampshire.
Marwell Hall and its estate in Colden Common came on the market which had almost everything John wanted - mature trees, undulating land, chalk sub-soil, near to big cities and people he hoped would want to visit his zoo.
However, this was not the case: "Naively I thought that everyone that lived near Marwell would love the idea - I thought they would see it as a delightful present - but they didn't react that way at all. They thought they were going to get eaten in their beds.
"Because of the opposition we had to have a planning enquiry so everything was delayed and cost us a lot of money. A sensible person would have stopped but I'm not a sensible person.
Hampshire County Council supported the attraction and the plans went ahead, but funds were still very tight.
John admits Marwell cost him more than £1m to set up.
He bought all the original animals - starting with a pair of Siberian tigers in Florida and that sped up securing the purchase of Marwell because he needed somewhere to put them when they came out of quarantine!
He explains: "I can't remember how much I spent on animals but I do remember selling my Rolls Royce to buy some zebras. Best thing I ever did actually!"
The zoo really struggled in the early years:"I was pretty worried actually when we opened - we were in debt and the visitors didn't come in the numbers I expected.
John focussed on African antelope early on, which was unusual for a zoo
"For a few years I wasn't sure we could afford to keep going. When VAT was introduced, we paid the government more VAT in a year than we made in surplus. We eventually won a court case that excused us from paying the tax, which helped our finances."
Other things that helped boost numbers and cash flow were the opening of the M3 motorway, bringing visitors from South London, and the introduction of brown tourist signs.
By 1978 John managed to achieve his ultimate goal of creating a charitable trust so his zoo and conservation work, for which he won an OBE, would last forever and it would become less of a personal risk for him.
"After we formed The Marwell Preservation Trust we really did begin to take off. If I had kept it private we never would have got to the size it is now and it wouldn't have got the major international stature that Marwell now enjoys."
Making a difference
Marwell has had an Education Department since 1982 and continues to run teaching sessions.
John says: "Education is very important because the younger generation have the future in their hands.
"Teaching is not just for youngsters - we went to great lengths right from the beginning to put up detailed signs to engage people's intellects - rather than have them just gawping at the animals.
John's wife, Margaret, playing with hand-reared Tig before he got too big
"Visitors need to know about he animals history and their part in our own evolution."
Marwell Wildlife - the new name for the zoo - still seeks to address causes of extinction and tries to manage populations of vulnerable species to ensure their survival.
This is achieved through a range of species and habitat conservation programmes locally through Marwell's base in southern England and internationally, with a particular focus in Africa.
Realising the dream
"I'm very happy that I started something and built it up to the point where whoever I meet in the South of England thinks what I have done is wonderful and the thought of the region without Marwell is unthinkable.
"And not just for crazy conservationists like me, but normal people who just appreciate it's values and what it adds to the community."
John Knowle's autobiography My Marwellous Life is published by Book Guild Publishing.