Prince Louis

The video, shared to the Duke and Duchess of Cambridge's official Instagram, shows Prince Louis, Princess Charlotte and Prince George asking veteran broadcaster and natural historian Sir David Attenborough questions about the environment.

It's believed to be the first time the children have spoken together on camera.

"We've got some questions for you, @DavidAttenborough," the post says.

In the video, Prince George asks Attenborough which animal he thinks will next become extinct.

Prince William and Kate Middleton’s youngest child turned two on Wednesday. To mark the occasion, they shared a set of images showing him with neatly combed hair and in a blue-and-white gingham shirt, playfully smiling at the camera.

In the pictures, Louis is seen flashing his hands, which are covered in a rainbow of paint colours.

The sweet pictures were taken earlier this month at Anmer Hall by the Duchess of Cambridge.

The couple's second son was born at 11:01 BST on Monday at the Lindo Wing of St Mary's Hospital in London, weighing 8lb 7oz.

A tweet from Kensington Palace said the baby would be known as His Royal Highness Prince Louis of Cambridge (pronounced Lou-ee, not Lou-iss).

The new prince is fifth in line to the throne.

Louis is one of the middle names of Prince William and of the new prince's brother, George.

It was also the first name of Lord Mountbatten - his great-great-great uncle - who was killed by the IRA in 1979.