A minor crush developed outside Buckingham Palace as hundreds of well-wishers flocked to see the iconic easel bearing news of the royal baby.
A bulletin detailing news of the baby was posted on the easel, a cornerstone of tradition surrounding the royal birth, at around 9pm, by Badar Azim, a footman with the Royal Household, and Ailsa Anderson, the Queen's press secretary.
A huge crowd developed within minutes, with cameras flashing everywhere. Stewards frantically tried to maintain order, demanding that visitors move away after taking their photo.
It is believed that no-one was injured in the pandemonium outside the palace gates.
One reveller who braved the delirious crowd told the BBC: "I've only just moved to London so I missed the wedding, Olympics and so on, so I had to be here. I'm proud to be British."
Meanwhile, outside St Mary's hospital a huge cheer went up as news of Kate's baby boy was broken.
Around half an hour after the birth was confirmed, town crier Tony Appleton bellowed out a message to the masses from the steps of the Lindo Wing, where the baby was born.
Appleton, dressed in traditional garb, finished on a familiar coda by saying: "May he be long-lived, happy and glorious, and one day reign over us. God save the queen."
'Diana would have been so happy'
The message was greeted with huge applause from the crowd, many of whom had waited hours for the birth.
One reveller shouted out: "Diana would have been so happy. She's a grandma!"
Another, Maria Scott, who had travelled down from the North East, told the Guardian: "I'm so, so happy". She continued by suggesting that the gender was not important, saying:
"As long as he's healthy and Catherine's alright, that's the main thing."