Surprise new addition to London Zoo

First ever baby sloth at London Zoo Photo: London Zoo

A pair of sloths have speeded up their usual slow dating game to produce London Zoo's first baby sloth - to the surprise of their keepers.

Zookeepers at ZSL London Zoo were shocked to discover two-toed sloth Marilyn was pregnant as they were unaware she had mated with male partner Leander, who arrived from Germany in 2012 to be paired with her.

The new baby with mum Marilyn Credit: London Zoo

Staff at the zoo had no idea the pair had acknowledged each other, but while they were playing it cool in public it seems that after hours the sloths had hit it off.

Two-toed sloths have been known to take nearly a decade to form a pair bond and breed, but factoring in an estimated 11-month pregnancy, it appears Marilyn and Leander were far from slow off the mark, taking six months to successfully mate.

New baby clings to mum Marilyn at the zoo Credit: London Zoo

"To say we were surprised when Marilyn fell pregnant is something of an understatement - we weren't aware that she'd even been near the male.

– Zookeeper Tegan McPhail

Keepers do not know the sex of the new arrival, which is spending its days clinging on to Marilyn, and will not be able to tell if it is a boy or a girl until it is scanned by vets as there are no external differences between males and females.