Duke and Duchess of Cambridge expecting their third child

The Duke and Duchess of Cambridge are expecting their third child, Kensington Palace has announced.

In a statement the palace said the duchess was suffering from severe morning sickness, as she did with her previous pregnancies, so a public engagement she had later on Monday had been cancelled.

The statement said: "Their royal highnesses the Duke and Duchess of Cambridge are very pleased to announce that the Duchess of Cambridge is expecting their third child.

"The Queen and members of both families are delighted with the news.

"As with her previous two pregnancies, the Duchess is suffering from Hyperemesis Gravidarum.

"Her royal highness will no longer carry out her planned engagement at the Hornsey Road Children's Centre in London today.

"The Duchess is being cared for at Kensington Palace."

The news was announced as the royal couple were preparing to send their eldest child, Prince George, off to school for the first time.

They have chosen a fee-paying independent school in a south London borough for their four-year-old son.

Thomas's Battersea will welcome the young prince and his parents on Thursday.

George's first day at school will also mark a new chapter for the Cambridges as they are now mainly based in their Kensington Palace apartment rather than their Norfolk home Anmer Hall.

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William, who quit his job as a pilot for the East Anglian Air Ambulance in July to become a full-time royal, is also due to attend the National Mental Health and Policing Conference in Oxford on Tuesday.

The couple's third child will be born fifth in line to the throne, bumping uncle Harry out of the top five and into sixth place.

The Prince of Wales is first in line, followed by William, Prince George and the couple's daughter Princess Charlotte, who is two.