Prince William (L), Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, present their newborn son outside St. Mary's Hospital in London, Britain, on April 23, 2018. Catherine on Monday gave birth to a boy, her third child, who is the fifth in line to the British throne. (Xinhua/Stephen Chung)
Royal baby: Duke and duchess show off new son
The Duke and Duchess of Cambridge have left hospital after the arrival of their third child, a boy.
The couple's second son, who was born at 11:01 BST, weighing 8lb 7oz, is fifth in line to the throne.
Prince George and Princess Charlotte had visited their brother at the Lindo Wing of St Mary's Hospital, London.
Leaving the hospital Prince William said the couple were very happy, before holding up three fingers and joking he had "thrice the worry now".
"We didn't keep you waiting too long this time," he added.
When someone asked him whether the couple had decided on a name, he said: "You'll find out soon enough."
Prince William and Catherine had come out of the hospital briefly to greet the crowds with their new son.
They then returned inside to put their newborn son in his car seat before driving away towards their home Kensington Palace.
Members of both families have said they are "delighted with the news" of the birth.
Kensington Palace said the name of the baby would be announced in due course while a formal notice of the birth had been posted on the forecourt of Buckingham Palace.
Favourite names at the bookmakers include Arthur, Albert, Frederick, James and Philip.
Prime Minister Theresa May tweeted her "warmest congratulations" to William and Catherine.
She said: "I wish them great happiness for the future."
Labour Party leader Jeremy Corbyn also sent his regards, tweeting: "Congratulations to Kate and William on the birth of their baby boy. I wish them all the very best."