Crowds have been gathering at Buckingham Palace to take photos of the formal notice announcing the birth of the royal baby.
- Copyright: PA
The bell ringers at Westminster Abbey will play Cambridge Surprise Royal at 13:00 BST tomorrow to celebrate the birth of the new prince.
Flags have been raised at Buckingham Palace and Windsor Castle to celebrate the birth of the third child of the Duke and Duchess of Cambridge.
The University of St Andrews has offered its congratulations to its two former students after the birth of their third child.
The Duke and Duchess of Cambridge met while studying at the university on the east coast of Scotland.
Some people had their fingers crossed that BBC newsreader Simon McCoy would be the one to announce the arrival of the new royal baby on air.
In October, he announced the baby’s due date with a characteristically dry delivery:
"Now, bearing in mind that they announced that she was pregnant back in September and it was thought that she was around two or three months pregnant, I’m not sure how much news this really is."
He added: "But anyway it’s April so clear your diaries, get the time booked off because that’s what I’m doing."
But the official announcement came just after 13:00 BST - an hour before Simon McCoy went on air.
The BBC wants to hear from anyone else who has had a baby today:
Figures from across the political spectrum continue to congratulate the Duke and Duchess.
Speaker John Bercow told the Commons: "I am sure the whole House would want to join me in sending Their Royal Highnesses, the Duke and Duchess of Cambridge, our warmest congratulations on the birth of their son."
Liberal Democrat leader Sir Vince Cable tweeted: "Congratulations to the Duke and Duchess of Cambridge on the birth of their son. I'm sure his older brother will be delighted he has been born on St George's Day! Best wishes to them all and Princess Charlotte."
Celebrities have been sending their congratulations to the Duke and Duchess of Cambridge.
TV presenter Paddy McGuinness, former world heavyweight champion boxer Frank Bruno and Hollywood actress Mia Farrow were among the celebrity well-wishers on social media.
While comedian David Walliams joked about the baby name announcement...
Two members of the royal household staff - footman Heather McDonald and senior footman Olivia Smith - putting the official birth notice up outside Buckingham Palace:
- Copyright: BBC
A notice bearing the news of the birth of the new prince has been placed outside Buckingham Palace according with tradition.
The framed notice was brought out of the Privy Purse Door and placed on an easel in the forecourt where it will remain for about 24 hours.Copyright: Stefan Rousseau/PA Wire
The practice of posting a bulletin announcing a royal birth has gone on for at least as long as Buckingham Palace has been the sovereign's official residence - since 1837.
After it comes down, the notice will be sent to the Privy Council Office so it can be kept in their records.
The new baby Prince of Cambridge weighed 8lb 7oz - heavier than both Prince George and Princess Charlotte.
Charlotte, at 8lb 3oz, weighed slightly less than George's 8lb 6oz - but was still above the average weight of a baby in the UK which is about 7lb 7oz (3.5 kg).Copyright: BBC
But the new prince is not the heaviest royal baby in recent years. That title falls to Savannah Phillips - the daughter of the Queen's grandson Peter Phillips - who weighed 8lb 8oz in 2010.
George was the heaviest future king to be born in recent history. Prince William weighed 7lb 1.5oz in 1982, while Prince Charles weighed 7lb 6oz in 1948. Prince Harry weighed 6lb 14oz in 1984.
The Queen - then Princess Elizabeth - was born by caesarean section in her maternal grandparents' London home and was also third in line to the throne at the time, but her weight was not announced, as was previously the custom for royal babies.
There will be many things that set the new royal baby's life apart from others, but something the prince will have in common with lots of us is siblings.
Linda Blair, a clinical psychologist and Daily Telegraph columnist, said third-borns often have certain personality traits.
"You get wiser parents with each kid. So third-borns grow up with more relaxed boundaries. These are the children most likely to be creative and risk-takers. They can try anything. That third kid has lots of people to look up to," she said.
The team that looked after the Duchess of Cambridge during the birth of her third child was led by Guy Thorpe-Beeston, surgeon gynaecologist to the royal household, and consultant gynaecologist Alan Farthing, surgeon gynaecologist to the Queen.
The pair (pictured left and right below) were both involved with the birth of Prince George in 2013.Copyright: PA WIRE
Dr Sunit Godambe, a consultant neonatologist at Imperial College NHS Trust, which runs St Mary's hospital, was also part of the group that cared for the duchess during her previous two births alongside Mr Farthing and Mr Thorpe-Beeston.
Professor Huw Thomas, physician to the Queen and head of the medical household, completed the team.
He was also involved with the birth of Princess Charlotte.
Before 06:00: The Duchess of Cambridge is driven to the Lindo Wing of St Mary's Hospital, Paddington, London, accompanied by the Duke of Cambridge.
08:24: Kensington Palace confirms Kate has been admitted to hospital in the early stages of labour.
11.01: Kate gives birth to a baby son.
13:02: Kensington Palace announces the birth of the prince and reveals the baby weighs 8lb 7oz (3.8kg).
With Arthur, Albert and Philip among the current bookies' favourites for a boy, it appears the public expect the royal couple to opt for a traditional name, rather than something more left-field.
But experts say there is a chance the ultimate name choice might also reflect the Middleton side of the family.
For their first two children, the duke and duchess chose traditional options, seen as a tribute to previous members of the Royal Family.Copyright: Reuters