This is the adorable moment a two-toed baby sloth was born at a London zoo – in a speedy birth which left zookeepers stunned.

A famously slow creature, the mother sloth – named Marilyn – gave birth within the short hour-long window between rounds on 24 October.

Her keepers at ZSL London Zoo had been checking on the pregnant mammal regularly, and noted that the expectant creature showed no signs of labour during the last check.

But when they came back to see her less than an hour later, she had already given birth and was snuggled up with her new cub – speedy work for the notoriously slow-moving species.

The zoo’s sloth keeper, Marcel McKinley, said: “We knew Marilyn was coming to the end of her pregnancy, so we’ve been keeping a close eye on her, arranging regular ultrasounds with the Zoo’s vet team and checking every day for signs of the new arrival.

“We looked in on her first thing and there was no baby - and no sign at all that she was labour.

“Less than an hour later I spotted something that looked like a tiny arm, tucked into Marilyn’s tummy.

“I called the rest of the team to confirm my eyes weren’t playing tricks on me, and they arrived just in time to see her turn around in the tree and give us the perfect view of her healthy newborn – who she’d quietly delivered, with no fuss at all, while we’d been chopping up sweet potato for her breakfast.

"She clearly took the whole thing in her stride.”

The cub has been named Terry after Terry March, one of the zoo’s longest-serving team members, who has been at the zoo since 1973.

Visitors will be able to find Marilyn and baby Terry in Rainforest Life, the only living rainforest in the city which is heated to 28°C.

The baby sloth’s sex is unknown until confirmed by vets after hair DNA is analysed.

Male or female, the newborn makes for a valuable addition and, once the sex is confirmed, its details will be added to the European Studbook (ESB) – part of a coordinated breeding programme for two-toed sloths.

Marcel added: “At two-weeks-old, Marilyn’s little one is doing really well. Two-toed sloths have a gestation period of 10 to 11 months and infants are already physically well-developed when they’re born, meaning they’re able to eat solid food right away.

“We’ve named the youngster Terry, after one of the Zoo’s longest-serving zookeepers – our colleague Terry March, who has devoted his whole life to caring for threatened species and educating the public about wildlife.”