It began with the tiger who wouldn’t come to tea. Cinta was so shy that she refused to feed when keepers at London zoo were around, and staff wondered how they would ever administer the young animal’s vaccinations without traumatising her.

So Tony Cholerton, a zookeeper who had been a motorcycle engineer for many years, invented Robovacc – a machine to quickly administer vital jabs without the presence of people.

The result, a clever contraption he controlled from an adjacent room with a handset taken from remote-control toy aeroplanes, successfully administered vaccinations to Cinta in a feeding area. The tiger sat up briefly, mid-meal, as the needle penetrated her rear end, then calmly continued eating.

Cholerton, who worked at London zoo for 30 years before retiring in late 2025, now hopes a fully developed automatic version of his invention could solve seemingly intractable wildlife challenges – such as the role of badgers in spreading bovine TB to cattle.

Badgers have been controversially culled in England for more than a decade, even while wildlife charities have been vaccinating badgers to show there is an alternative to killing Britain’s largest surviving carnivorous wild animal. The main cause of bovine TB in cattle is other cows.

Badger vaccination can help, but it is expensive and time-consuming, and requires catching badgers in traps where they are often held for several hours overnight before they can be injected by a trained vaccinator.

In contrast, Cholerton’s fully automated Robovacc machine, known as Autovacc, could administer vaccinations to a colony of up to 20 badgers without human intervention, with each badger being detained for no longer than a minute or two.

“The dream is to see it used by scientists and farmers,” said Cholerton, who believes his prototypes could be mass-produced cheaply. “This is about giving the scientists the means to show that the science is correct, and badger vaccination works. The farmers win because they have a means to solve the TB problem in cattle. Everyone wins.”

After Cholerton invented Robovacc, vets at London zoo used versions of his machines to deliver vaccines to lions and Diana monkeys. He found it worked best on carnivores, which tolerate the pin-prick, unlike primates, which remember the experience and then avoid the machine. Cholerton said it could be particularly useful to vaccinate captive carnivore species such as Amur leopards, when keepers wanted to keep human interactions to a minimum so they could be returned to the wild.

While working as a zookeeper for the past decade, Cholerton spent evenings in his east London flat finessing his invention, developing a fully automatic version that uses three sensors to detect the proximity of the muscular rear end of an animal.

The machine for badgers has been tested on ring-tailed coatis, which, like badgers, are unafraid of entering tunnels.

The animal is tempted by a food bait into a Perspex tunnel, where smart technology is used to prevent the same animal being vaccinated more than once. When an animal is vaccinated, it is sprayed with nanoparticles that stick to the fur. These activate sensors if the animal returns, and a door opens into a different section of tunnel through which the animal exits.

If an animal has not been vaccinated, another door opens into the vaccination section of the tunnel, where the animal’s movement is briefly restricted so its hindquarters rest against the sensors. In a split second, a needle is triggered from behind a protective sheath and injects the animal.

Several safety mechanisms ensure the animal cannot bend or break the needle, or leave the tunnel with a needle still in its body. After the injection, the doors open and the animal is released.

Cholerton hopes the next stage will involve conservation scientists, charities that have been overseeing badger vaccination and even interested farmers trialling his Autovacc machine.

“This has got to be a collaboration,” he said. “The more interest the better. It would just be nice to see it being used with wild animals and undertaking vaccinations in a way that isn’t too invasive.

“If it works for badger vaccination in a humane way, whatever government is in power will be obliged to take this route rather than just culling animals.”

Rosie Wood, the chair of Badger Trust, said: “Vaccination of any wild species is stressful for the animal concerned so it’s heartening to know that jab-shy captive wild species can now be vaccinated stress free. There are many possible future applications for the technology – most I suspect are ones we haven’t thought of yet but might be the next zoonotic pandemic, so investment in it should be taken seriously.”

But Wood added that although vaccinating badgers could be used to prove that badger populations were kept bovine TB-free, it did not have any measurable effect on the rates of bovine TB in cattle. “Even Defra now concedes it is not possible to prove any measurable impact on bovine TB rates in cattle as a result of badger culling – and as killing them isn’t working, vaccinating them won’t either,” she said.