A caged monkey concealed beneath a laundry bag was found abandoned on a London bus by a shocked driver.

The terrified common marmoset was discovered last Friday at 11.43am on board the 302 bus, travelling between Mill Hill Broadway Station and Kensal Rise.

The driver had pushed the laundry bag out of the way for a mother and her pram trying to move down the bus, only for the bag to start 'chirping and jumping around'.

It was then that the driver peered behind the bag and discovered the tiny primate quivering inside the cage.

He drove her back to the Metroline Bus Depot at Willesden Bus Station and contacted the RSPCA for help.

RSPCA London Chief Inspector Clare Dew, who is now investigating the incident, said: 'A mum got on the bus with her buggy but couldn't get down the walkway because the laundry bag was sticking out of the luggage bay and blocking the way.

'The driver came to help her and, as he pushed the bag out of the way, the monkey inside started chirping and jumping around. When he peered inside the bag he spotted the frightened marmoset.'

The unmicrochipped monkey has since been rescued and aptly named Oyster - after the London travel card.

The terrified marmoset was discovered inside a cage covered by a laundry bag on board a London bus

The primate has since been rescued and aptly named Oyster - after the London travel card

The common marmoset is a tiny monkey, weighing between 250 and 400g, native to northeastern Brazil.

They are instantly recognisable by the prominent white tufts of hair on their ears and a white blaze on their foreheads.

Although it was given a clean bill of health, its abandonment on board public transport is feared to be part of a wider trend, due to a change in law introduced in April.

The new legislation dictates that all primates kept in England must be licensed. Charities like the RSPCA now fear that owners unable to meet the requirements may illegally dump the animals as a result.

RSPCA Exotic Animals Expert Evie Button said: 'Primates are highly intelligent and social wild animals who need a lot of space, mental stimulation and appropriate companions - needs that can't be met by human company alone.

'The introduction of primate licenses in England is an important step forward for animal welfare, helping to ensure these animals are kept in more appropriate conditions, but there is a real concern that keepers who cannot or do not want to license their pet may now instead abandon them.

'With the UK Government estimating 5,000 primates being kept as pets in England and our friends at Born Free reporting very little uptake of the new license system, we're concerned about what has happened to many of these animals.'

The charity called on the public to help officers track down the circumstances behind the shocking abandonment. People who may have seen someone board the bus with the laundry bag are being asked to contact the appeal line on 0300 123 8018.

Chief Inspector Dew added: 'The monkey - a female common marmoset - was inside a small, white, metal bird cage which had been wrapped inside a plastic, chequered laundry bag, with handles, so was well-concealed.

'She'd been left with some apple but was, understandably, very stressed and dehydrated.

'We'd like to say a big thank you to the bus driver and the team at Metroline who stayed calm, took the monkey back to their station, put her somewhere dark and cool, to keep her calm, and contacted us for help.

'They've been incredibly helpful and are now assisting with our enquiries so we can trace the person responsible for dumping her.'

She continued: 'No one noticed anything unusual on the bus before the monkey was discovered but we'll be looking at CCTV and the logs for scanning on and off the bus to see if we can locate the person who left her onboard. It was clearly intentional.

'This is clearly a direct result of the new legislation and is something we feared would happen. I'd be surprised if it's the last primate we see being dumped.

'But what we would say to anyone who is struggling to care for a pet or who cannot get a licence for any primate they have, please speak to specialists, vets or charities, don't abandon them as it can have tragic consequences.'

Oyster the marmoset has now been rescued and is settling into a sanctuary with specialist primate facilities. She will soon be introduced to a new male companion who had been looking for a friend.

Chief Inspector Dew added: 'In a twist of fate, a sanctuary had been working with us to find a suitable female marmoset to introduce to a lone male they were caring for.

'We were hoping to transfer one from the north of England but, when that fell through just a few hours before Oyster was rescued, it looked like destiny that Oyster was supposed to go there.

'She's settled in really well over the weekend, and is eating well, so hopefully she'll be able to meet her new friend soon. If she isn't claimed then she'll remain there with experienced keepers, a wonderful enclosure and company.'

Warnings have been issued about reports that there is limited compliance with the new licensing legislation for primate keepers.

RSPCA data revealed that between 2021 and 2025, rescuers dealt with 238 reports of primate neglect and cruelty.