Hundreds of royal well-wishers gathered at the gates of Buckingham Palace this afternoon, as news of the new prince's arrival was announced in a tradition which stretches back to the 19th century.
The crowd waited patiently for the formal notice of the arrival of the fifth in line to the throne, which involves the presentation of a bulletin, placed on a golden easel in front of the palace.
The ritual dates back to at least 1837, when Buckingham Palace became the sovereign's official residence.
At 2:30pm senior footman Olivia Smith and footman Heather McDonald strode across the gravel at the front of Buckingham Palace to the roar of a delighted crowd, and placed the notice on the easel.
The bulletin had details of the birth, including the 11:01am delivery time as well as the signatures of the senior medical team who cared for the Duchess of Cambridge.
The notice read: "Her Royal Highness the Dutchess of Cambridge was safely delivered of a son at 11:01 today. Her Royal Highness and her son are both doing well."
In the crowd was Luigi Ritacca. He was celebrating his 31st birthday and said he felt happy to share the day with the new royal arrival.
"I'll never forget the date, that's for sure," he said. "Of course, it's stolen my thunder a little, but as long as they don't name him Luigi, I'll be fine," he added.
John and Susan Gill were having tea at the Ritz when they heard the news of the birth.
"A lady stood up and raised a glass of champagne and said: 'to the new prince," said Susan.
They then walked down to Buckingham Palace to soak in the atmosphere.
"This is what Britain is all about," added John. "The more the merrier."
Vicky and Mike Greenslade arrived at the palace as soon as they heard the news of the royal birth.
"It's a great atmosphere, and very well organised," said Mike. "It's very British," added the 71-year-old.
The easel is set to stand in front of the palace for 24 hours. When it is taken down, it is sent to the Privy Council Office so that the details of may be recorded in the Privy Council records, according to the palace.