Duke and Duchess of Cambridge expecting third child

The family of four are set to become five, with a new baby on the way.

Prince William and the Duchess of Cambridge are expecting their third child.

Buckingham Palace told everyone the news on Monday morning, adding that the Queen is "delighted".

It'll make it a big week for Kensington Palace, with four-year-old Prince George due to start school on Thursday.

Now he and two-year-old Princess Charlotte can get used to the idea of having a future new brother or sister as well!

Prince George was born on 22 July 2013 at St Mary's Hospital in London.

William and Kate's third child will become the fifth person in line to the throne.

This is the line of people who could go on to be King or Queen.

The new child will be behind their granddad, Prince Charles, dad, Prince William, and siblings Prince George and Princess Charlotte.

If it is a boy, Charlotte will be the first girl to be ahead of their brother in the line to the throne.

This is because of new rules that started in 2015.

Princess Charlotte joined the Royal family almost two years later on 2 May 2015.

Prince George and Princess Charlotte often travel with their parents, so the new baby could join them on foreign engagements in the future as well.