Postpublished at 12:36 British Summer Time 2 May 2015
Here it is! The official announcement of the birth, on the gold-coloured easel, will be inspected and photographed by crowds of visitors outside Buckingham Palace during the day.
Summary
The Duke and Duchess of Cambridge have left hospital with their new baby daughter, who slept throughout
The new princess was born at 08:34 BST (07:34 GMT), on 2 May, 2015, two-and-a-half hours after the Duchess of Cambridge was admitted to hospital
Prince William told reporters he was "very happy" at the arrival of his second child
The duke brought Prince George to the hospital so that the young prince could meet his sister
The name of the baby, fourth in line to the throne, is yet to be announced
Postpublished at 12:36 British Summer Time 2 May 2015
The easel momentpublished at 12:33 British Summer Time 2 May 2015
The official notice of the new princess's birth is mounted on an easel in front of Buckingham Palace
News around the worldpublished at 12:29 British Summer Time 2 May 2015
News of the royal birth is, as you might expect, already making headlines across the world. In Australia, the Sydney Morning Herald has carried the story on its front page saying: "A sister for George!" Meanwhile, in Pakistan, broadcasters interrupted bulletins to show the royal announcement being made.
Get involvedpublished at 12:28 British Summer Time 2 May 2015
Katrien Grobler is on a visit to London from South Africa and is just outside the Lindo Wing. She says: "I arrived about five minutes before the announcement. I'm shaking with excitement, the atmosphere is amazing. There are at least 1,000 people here. Most of them are photographers! There are people with flags; people just want to be part of it. It's part of history and I just want to be here!"
Image source, @PrincessKatrienSilver penniespublished at 12:27 British Summer Time 2 May 2015
Of course, the royal princess is not the only baby being born today. The Royal Mint has said it is to give 2,015 babies born today a lucky silver penny in keeping with the tradition.
If you are a parent in that position, you can apply for it by visiting the Royal Mint's Facebook page., external If you are a parent of a baby born today and are reading these live updates, then we send our admirations as well as our congratulations.
Message from the flight deckpublished at 12:20 British Summer Time 2 May 2015
Image source, Royal NavySailors on board HMS Lancaster, known as the Queen's Frigate, have sent their own unique message of congratulations, by spelling out the word "sister" on the flight deck.
Crowds at the palacepublished at 12:19 British Summer Time 2 May 2015
People have started gathering outside Buckingham Palace, where a formal announcement of the royal birth is expected to be posted on an easel at about 12:30 BST.
Get involvedpublished at 12:17 British Summer Time 2 May 2015
Elaine Stratford from Cambridgeshire emails: Fantastic news for Kate and William - the safe arrival of a baby daughter and playmate for gorgeous George.
A princess is bornpublished at 12:17 British Summer Time 2 May 2015
The new girl is officially the Princess of Cambridge, after the Queen made a change after the birth of Prince George (aka the Prince of Cambridge) to allow for his future siblings to be princes and princesses. Before that, only the eldest son of the eldest son of the Prince of Wales was automatically granted that title.
The last Princess of Cambridge was King George III's granddaughter Princess Mary Adelaide of Cambridge who was born in Hanover, Germany, in 1833.
A princess is bornpublished at 12:17 British Summer Time 2 May 2015
The new girl is officially the Princess of Cambridge, after the Queen made a change after the birth of Prince George (aka the Prince of Cambridge) to allow for his future siblings to be princes and princesses. Before that, only the eldest son of the eldest son of the Prince of Wales was automatically granted that title.
The last Princess of Cambridge was King George III's granddaughter Princess Mary Adelaide of Cambridge who was born in Hanover, Germany, in 1833.
Postpublished at 12:08 British Summer Time 2 May 2015
Nicholas Witchell
Royal correspondent"The question now of course is whether we will see the family, whether we will see William and Catherine and their new daughter leave the hospital today. I'm told that has not been ruled out."
Get involvedpublished at 12:06 British Summer Time 2 May 2015
Patricia Strnad from California, USA emails: Congratulations to the Duke and Duchess of Cambridge upon the speedy, healthy and happy delivery of their very own "Little Princess"! I am extremely thrilled and happy with the news!
Postpublished at 12:05 British Summer Time 2 May 2015
Image source, EPASpeculation now will turn to what name the duke and duchess will give the baby princess - Alice remains the favourite with bookmakers.
Get involvedpublished at 12:03 British Summer Time 2 May 2015
Catherine Smoors from Tasmania, Australia emails: Congratulations to the Duke and Duchess and charming Prince George on the birth of their beautiful new daughter and sister.
Postpublished at 12:02 British Summer Time 2 May 2015
Former press secretary to the Queen, Charles Anson, speaking on the BBC News Channel, explains that when the happy parents do choose the name for their new baby, the custom in the royal family is that the Queen has to approve their choice.
Postpublished at 12:02 British Summer Time 2 May 2015
Katie Nichol, royal biographer
Prince William has always wanted a little girl, and a little sister for Prince George. It's wonderful, it's been a long time since we've had a princess, and what a historic princess this will be, because of course she will not be overlooked in the succession, because of those revisions to the laws, and rightly so."
Postpublished at 12:00 British Summer Time 2 May 2015
BBC royal correspondent Nicholas Witchell - who put on a blue and pink striped tie this morning as the world waited to hear if the baby was a boy or a girl - says the royal couple and the princess could leave hospital today, saying it "certainly hasn't been ruled out".
He will be reporting from outside the Lindo Wing during the rest of the day - and possibly longer - until the royal couple emerge with their newborn.
Postpublished at 11:56 British Summer Time 2 May 2015
The baby princess was born weighing 8lbs 3oz (3.7kg) - in comparison Prince George weighed 8lb 6oz (3.8kg) when he was born in July 2013.
Postpublished at 11:52 British Summer Time 2 May 2015
Image source, ReutersThe scene outside the Lindo Wing at St Mary's Hospital, where large numbers of press and members of the public converged after news broke that the duchess had gone into labour.
Postpublished at 11:49 British Summer Time 2 May 2015
Meanwhile, Ukip leader Nigel Farage tweeted, external: "Congrats on the new #RoyalBaby. Today is a great day for celebration!"