It had all the hallmarks of a Hollywood classic: The Great Escape all over again, with the two heroes in the title roles tunnelling their way to freedom – but with a tragic ending.
The high drama began yesterday at 10am, when Coco and Jonnie, both chimps, managed to escape from their enclosure at Whipsnade Zoo in Bedfordshire. The pair, whose species are known for their digging prowess, are thought to have tunnelled under their enclosure, making a cunning effort to gain freedom.
Zookeepers gave chase within minutes and though Coco, in her thirties, was easily rounded up Jonnie, an elderly chimp at 41-years-old, was more determined.
As keepers pursued the animals, visitors were warned to stay behind a cordon or were led to secure locations.
''Both are known as rascals," one keeper said. ''Jonnie can be a bit of a thug and we once had to put a sign outside Coco's cage saying, 'Beware: Coco spits and throws poo at people.' But we don't actually believe either was dangerous."
The zoo immediately deployed its escaped animal procedure, leading visitors to safety.
''Keepers moved quickly to recapture the chimps," a zoo spokesman said yesterday. ''No staff or members of the public were injured. But in the interests of public safety, Jonnie was shot. That is normal practice if a chimp cannot be recaptured. But at no stage was the safety of our visitors at risk."
Last night, with Coco back behind bars, the zoo launched an investigation to discover how the pair got away. The most likely theory was that they had dug an escape tunnel under the tall enclosure fence, built three years ago, although nothing was immediately found.
''We have made sure the enclosure is now escape-proof," said one keeper. ''But for the life of me I can't work out how they got out in the first place. Tunnelling seems the most likely method."
The zoo has six other chimps: Nicky, 23; Bonnie Louise, 21; Zephyr, 15; Grand and Phil, 11, and five-year-old Elvis. Jonnie and Coco lived at London Zoo with Cherry, Coco's mother, until last year. Before that, mother and daughter were kept at separate zoos for 25 years but when they were reunited in 1998 they recognised each other immediately.
David Field, the zoological director of London Zoo, who has known Jonnie and Coco for years, said: "It may have seemed a bit like a comic caper, but this had a tragic ending and has left us all devastated.
"It will also upset the other chimps, and particularly Coco who will be trying to understand where he has gone. The two of them were real characters and they had a roller-coaster relationship. Jonnie had a gentle disposition whereas Coco was more inquisitive. She was probably the ringleader."
Whipsnade Zoo had only just opened when the drama was played out yesterday, although all members of the public were ushered out of the zoo before the keepers attempted to round up the chimps.