The Duchess of Cambridge has left hospital after giving birth to a son weighing 8lbs 7oz.

Kate and Prince William have returned home to Prince George and Princess Charlotte with their newborn son.

The baby boy was calm as he made his public debut.

The newborn prince
(John Stillwell/PA)

There were waves and smiles for wellwishers.

The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington
(Kirsty O’Connor/PA)

Kate looked thrilled as she left the hospital with her third child.

The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital
(Aaron Chown/PA)

The proud parents stood on the steps of the Lindo Wing as the media took the coveted first snaps of the new prince.

The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing
(John Stillwell/PA)

Kate was resplendent in red as the happy couple showed off their newborn son.

The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London
(Aaron Chown/PA)

The Duke and Duchess of Cambridge have left hospital with their new son.

The celebrations won’t stop today – royal salutes will be fired at Hyde Park and the Tower of London tomorrow.

A statement added: “Prince George and Princess Charlotte have now returned to Kensington Palace.

“Their Royal Highnesses would like to thank all staff at the hospital for the care and treatment they have received.

“They would also like to thank everyone for their warm wishes.”

The Duchess of Cambridge will be heading home with her newborn son this evening, Kensington Palace has confirmed.

The swirling wind played with George’s hair as the prince, wearing his school uniform, shyly made his way out of the car and into the hospital.

Prince George arrives to meet his newborn brother at the Lindo Wing at St Mary's Hospital in Paddington, London
(Dominic Lipinski/PA)
Prince George holds his father's hand as he arrives to meet his newborn brother at the Lindo Wing at St Mary's Hospital in Paddington, London
(Dominic Lipinski/PA)

Here are some clips of their arrival – Charlotte’s already a pro at the official royal wave.

The young royals will meet their baby brother for the first time.

The next time they step out of this door, it will be as a family of five.

The Duke of Cambridge with Prince George and Princess Charlotte arriving at the Lindo Wing at St Mary's Hospital
(Kirsty O’Connor/PA)

A bank of photographers were primed for their arrival.

The Duke of Cambridge with Prince George and Princess Charlotte arriving at the Lindo Wing at St Mary's Hospital in Paddington, London
(Kirsty O’Connor/PA)

Charlotte showed off her royal wave, as George smiled shyly.

Princess Charlotte holds her father's hand as she arrives to meet her newborn brother at the Lindo Wing at St Mary's Hospital in Paddington
(Dominic Lipinski/PA)
The Duke of Cambridge with Prince George and Princess Charlotte arriving at the Lindo Wing (Kirsty O'Connor/PA)
(Kirsty O’Connor/PA)

Prince George and Princess Charlotte have now arrived to see their baby brother.

The Duke of Cambridge with Prince George and Princess Charlotte arriving at the Lindo Wing at St Mary's Hospital
(Kirsty O’Connor/PA)

William was beaming as he left the Lindo Wing.

The father of three is making the short journey to Kensington Palace.

“Back in a minute…”

The duke is expected to return to the hospital with his other children.

He did the same when Charlotte was born, bringing Prince George to see his new sister before leaving with wife and baby shortly afterwards.

The Duke of Cambridge leaving the Lindo Wing
(Aaron Chown/PA)

William was all smiles as he waved to those waiting outside.

The Duke of Cambridge leaves the Lindo Wing at St Mary's Hospital in Paddington, London
(Kirsty O’Connor/PA)

The Duke of Cambridge has just left the Lindo Wing.

The Duke of Cambridge drives away from the Lindo Wing
(Kirsty O’Connor/PA)

Excitement is building outside the hospital.

Labour leader Jeremy Corbyn and former prime minister David Cameron have also tweeted their congratulations.

If the easel at Buckingham Palace is traditionally old school, then here’s the modern equivalent.

Congratulations are continuing to pour in for the royal couple.

Will the Queen be amused? A smiling waxwork of the monarch has been driven past the Lindo Wing in a taxi as the waiting press pack look on.

A waxwork of the Queen is driven past the Lindo Wing at St Mary's Hospital in Paddington in a taxi
(Kirsty O’Connor/PA)

There are more cameras than usual outside the gates of Buckingham Palace as wellwishers take snaps of the pronouncement.

Tourists and photographers take pictures of a notice on an easel in the forecourt of Buckingham Palace in London to formally announce the birth of a baby boy to the Duke and Duchess of Cambridge at St Mary's Hospital
(Stefan Rousseau/PA)

The new Prince of Cambridge has taken his place in the line of succession, slotting in ahead of Prince Harry.

Line of succession
(PA Graphics)

Flags are flying to mark the happy news.

The Duke and Duchess of Cambridge will be greeted by this sight when they leave the Lindo Wing with their newborn child.

The easel has landed.

Kensington Palace has said the name of the baby will be announced in due course.

The bulletin announcing the royal birth has been put on display outside Buckingham Palace by footman Heather McDonald and and senior footman Olivia Smith.

(Stefan Rousseau/PA)
(Stefan Rousseau/PA)

The notice reads: “Hey Royal Highness the Duchess of Cambridge was safely delivered of a son at 11.01am today.

“Hey Royal Highness and her child are both doing well.”

The easel was put on display at 2.30pm.

(Stefan Rousseau/PA)
(Stefan Rousseau/PA)

It will remain in place for around 24 hours.

(Stefan Rousseau/PA)
(Stefan Rousseau/PA)

Well wishes are pouring in from all quarters.

Here’s the moment a Town Crier announced the news.

The London Eye will be changing its colour later to mark the birth of the Cambridge’s second son.

Hot off the press.

Politicians are celebrating the royal birth.

And Theresa May’s not the only resident of Number 10 to offer congratulations.

Twitter is awash with messages of congratulations for William and Kate.

Customers and staff outside the Duchess of Cambridge pub in Windsor celebrate the news.

(Jonathan Brady/PA)
(Jonathan Brady/PA)
(Jonathan Brady/PA)
(Jonathan Brady/PA)

David Walliams has shared some fake news.

Celebrations among royal fans are breaking out outside the hospital.

(Kirsty O'Connor/PA)
(Kirsty O’Connor/PA)
(Kirsty O'Connor/PA)
(Kirsty O’Connor/PA)

Prime Minister Theresa May has congratulated the happy couple.

Congratulations are coming in for William and Kate.

But what will the royal couple’s new baby boy be called?

Kate gave birth in Paddington, so this little chap’s got something to say.

Funnyman David Walliams has waded in with a light-hearted low blow at Prince Harry.

TV historian Kate Williams is among those waiting with the press pack.

Will we see the Duke and Duchess of Cambridge walk through those doors today?

We can only speculate over what the new royal’s name will be. But one punter clearly fancies Arthur.

The birth will be declared in both conventional and contemporary ways.

An announcement will be emailed to the press and a celebratory tweet posted on the Kensington Palace Twitter feed – @KensingtonRoyal.

There will also be the traditional custom of placing a framed paper proclamation on an ornate gold stand behind the iron railings of Buckingham Palace.

There was a brief flurry of excitement when an unsuspecting couple emerged from the Lindo Wing with their newborn baby to be greeted by the world’s media.

The Lindo wing at St Mary's Hospital
All eyes are on the Lindo Wing (Kirsty O’Connor/PA)

They posed for photographs outside the famous door in front of dozens of journalists and photographers before leaving in a taxi.

We’re in a perfect position to show you William, Kate and their third little bundle of joy when they emerge from St Mary’s.

William and Kate don’t know the sex of their third child yet but, one thing’s for sure, the new arrival will be fifth in line to the throne.

Younger siblings are no longer allowed to jump ahead of their older sisters in the line of succession.

It is understood Kate was taken to the private maternity unit of St Mary’s hospital before 6am.

When the duchess was pregnant with Princess Charlotte her labour began in similar circumstances, with Kate being admitted around the same time and her daughter born a few hours later.

(Dominic Lipinski/PA)
(Dominic Lipinski/PA)

Royal fan Sharon McEwan has been camping outside the Lindo Wing waiting for this moment.

(Dominic Lipinski/PA)
(Dominic Lipinski/PA)

John Loughrey, 63, is part of a group who have been camped outside the hospital. He said: “I’m so pleased it’s St George’s Day. St George himself would be very pleased if the baby’s born today.”

Mr Loughrey, from Streatham, south London, said he plans to celebrate the birth with English flags and a portion of fish and chips.

(Dominic Lipinski/PA)
(Dominic Lipinski/PA)

“It doesn’t matter if it’s a boy or a girl as long as it’s a healthy baby and a healthy mother,” he said. “It’s very good for our country and of course Her Majesty the Queen.”

Another member of his group, 82-year-old Terry Hutt, also welcomed the news.

“It’s fantastic to have another new-born baby,” said Mr Hutt, who turns 83 at the end of the month and was hoping to share his birthday with the new royal. “If they were born on my birthday, I would have got a birthday cake.”

Meanwhile, royal fans are talking to members of the media as anticipation of the arrival of Kate’s third child grows.

(Dominic Lipinski/PA)
(Dominic Lipinski/PA)
(Kirsty O'Connor/PA)
(Kirsty O’Connor/PA)

Excitement is building outside the Lindo Wing where some royal fans have been camped out for 15 days.

Royal fans John Loughrey (left) and Terry Hutt hold dolls outside St Mary's Hospital (Dominic Lipinski/PA)
Royal fans John Loughrey (left) and Terry Hutt hold dolls outside St Mary’s Hospital (Dominic Lipinski/PA)

The world’s media is watching.

(Kirsty O'Connor/PA)
(Kirsty O’Connor/PA)

Police officers are stationed outside the Lindo Wing.

(Kirsty O'Connor/PA)
(Kirsty O’Connor/PA)

Here’s where William and Kate’s new arrival will fit into the Royal Family’s family tree.

Commentators speculate on the baby arriving on St George’s Day.

The world’s press is set up outside the hospital – hoping to be the first to catch a glimpse of the newest addition to the Royal Family.

Early on Monday morning, Kensington Palace announces Kate has gone into labour.