The Duchess of Cambridge has given birth to a new prince.

Prince William was by her side as Kate “safely delivered” a son at 11.01am (UK time) on Monday, according to a tweet from Kensington Palace.

The little boy weighed 3.8kgs, and mother and child “are both doing well”, the palace said.

A minute after the birth announcement, the palace tweeted that the royal family including the Queen – who protocol dictates is the first to hear the news of family babies – were “delighted” by news of the arrival.

“The Duchess of Cambridge was admitted to St Mary’s Hospital, London, earlier this morning in the early stages of labour,” Kensington Palace said in a statement released shortly after 8.20am (UK time).

People did not have to wait long to see the new prince.

Kate, wearing a red dress by Jenny Packham – whose designs she has worn to leave hospital with all three of her babies – smiled at hundreds of well-wishers and assembled journalists as she left the hospital cradling her baby just seven hours after the birth.

“Thrice the worry now,” William told reporters, holding up three fingers with a smile, as he got into the Land Rover to take his wife and newborn back to Kensington Palace.

“We didn’t keep you waiting too long this time.”

“Very happy, very excited, thank you,” he said.

The baby has yet to be given a name. Bookmakers have made Albert, Arthur, Jack and Fred the favoured names for a boy.

What do you think Williams and Kate will name their new baby?