The monkey house is in a frenzy. Overhead a procession of capuchins, a small and disarmingly intelligent primate normally found in the forests of Central and South America, streams across a specially designed walkway. The occasional yelp pierces the thick humidity of the enclosure as they climb, pick and stuff their faces with food in a constant blur of activity.
The fact that these diminutive animals are revelling so vigorously in their new-found space is perhaps unremarkable considering that, for the previous 20 years, they were entombed in tiny, individual stainless steel cages, suspended from the wall of a laboratory in Santiago, Chile. For most, the only occasions on which they left these solitary redoubts were to undergo experimentation by scientists working for the pharmaceutical industry.
Some bear visible scars of their time in the lab – angry gashes running the length of their rib cages. Others have been operated on as recently as four weeks ago. All have been saved from a life that bore little resemblance to that which nature intended.
The person who has delivered them to what could one day be a near-normal existence is Dr Alison Cronin, the director of Monkey World, the ape rescue centre nestling in Dorset's bucolic Frome Valley. In a triumphant culmination to an 18-month project – the largest rescue operation for non-human primates ever staged – this Californian-born scientist has brought all 88 monkeys safely to the UK to begin the long process of rehabilitation.
The animals touched down at Bournemouth airport last week after undergoing a gruelling, 18-hour flight on board a Chilean air force Hercules transport. The long flight followed months of painstaking preparations and negotiations and now, after so many years in captivity, she must begin the process of allowing her charges to be monkeys again.
The rescue has a profoundly personal dimension for Dr Cronin. Monkey World was founded in 1987 on the site of a former pig farm near Wool by her late husband, the conservationist Jim Cronin. Today, it commands an international scientific reputation, draws 500,000 visitors each year and boasts the largest collection of chimpanzees outside Africa.
But last year, Jim Cronin died from liver cancer at the age of 55. His wife says she never considered giving up the project she had helped create for the past 15 years and was determined to see through the Chilean operation despite her all-too-apparent grief.
"I had been working with primates before I met Jim but we shared a passion. To lose my husband at such a young age was a tragedy and deeply unexpected but I didn't see why I should lose my occupation too. Sometimes it seems easier to throw yourself into your work rather than confront your personal problems," she says.
The Cronins, both Americans, met in the UK. Jim had been working with the maverick conservationist James Aspinall at Howletts Wild Animal Park in Kent. Increasingly concerned at the plight of chimpanzees being worked as photographers' props on the beaches of Europe, he vowed to find a home for all of them. She, meanwhile, had been completing her studies at Cambridge and had begun working with rescued dancing bears. The two met, married and spent years travelling the world, working undercover to rescue monkeys enduring horrors at the hand of humans. It is a crusade she now intends to continue alone.
Dr Cronin, publicly at least, refuses to condemn the use of primates in scientific research and even pays tribute to the laboratory for taking the decision to call on her and her staff's expertise when it decided to put an end to its experiments.
"For them, the easiest option would have been euthanasia... But they wanted to try and give the animals some sort of quality of life," she says. Indeed, the staff in Chile took risks of their own in order to save the monkeys, having been subjected to death threats by animal rights extremists in their own country.
But while Dr Cronin will not comment on the politics of vivisection, she is more than happy for the world to know about the conditions in which animals are kept – not just abroad but in Britain too. "I have been in a lot of facilities and these were grim and antiquated by any standards. They were in these one-metre cages, suspended off the ground at waist height; the animals were in solitary confinement. When we first visited them, they began screaming. When they see a human ... often it means that something unpleasant is going to happen to them."
The years of incarceration have taken their toll physically and mentally on the capuchins.
"Their tails, which should operate as a prehensile fifth limb, vital in animals that spend most of their lives swinging from the branches of trees, had become virtually redundant. All have suffered from muscle wastage. They had also lost the ability to monkey around. They had no way of judging distances when they were leaping and jumping and at first when we put them in they were missing the branches and falling to the ground," she says.
But their instinct to climb was so powerful that, within 24 hours, many had got the hang of the long-forgotten skill. Yet while the muscle tone and movement will return, psychological problems are harder to address.
"Those that have been in the laboratory for a long time are institutionalised and some of the youngsters have deep emotional scars. Because we cannot talk to them, it is impossible to assess whether they are clinically depressed. But we can tell from how close their behaviour is to that in the wild, what condition they are in," says Dr Cronin.
Some are so used to being in their cages that, at first, they simply refused to come out, showing classic symptoms of agrophobia. Others merely spun around on the spot or repeatedly bashed their heads against the nearest object. The more seriously damaged monkeys ripped their own flesh.
But after patient coaxing, Monkey World staff are delighted at the rapid progress the capuchins have made and soon they will be allowed to enter the vast outdoor enclosures that will form their home. Dr Cronin sums up the vast effort being made on their behalf. "They have never felt the wind on their face or the sun on their back, or the soft ground beneath their feet. They don't know what it feels like to catch insects or butterflies. This is a welfare exercise to provide a proper and good retirement home for 88 monkeys who have never seen the light of day," she says.