After Kate Middleton gives birth to the royal baby, Prince William’s first call will be to his grandmother, Queen Elizabeth II, on an encrypted phone.
At the same time, the Duke and Duchess of Cambridge’s private secretary, Jamie Lowther-Pinkerton will inform PM David Cameron and a small number of other highly placed individuals, including the Archbishop of Canterbury.
Back at Buckingham Palace, officials will notify the head of each of the 54 Commonwealth countries and the First Ministers of Scotland, Wales and Northern Ireland.
For the public, an official notice announcing the birth will be placed in a glass-fronted easel and attached to the gates of the Palace.
Within minutes, depending on the time of day, a 41-gun salute will ring out in Hyde Park. Visitors will then begin turning up at St Mary’s Hospital.
The Middletons are likely to take centre-stage along with Prince Charles, the Duchess of Cornwall and Prince Harry.
Friends and other relatives will be encouraged to wait to see the baby when it gets home.
A source said the Queen will wait for the “baby to be brought to her”.
And although he or she will one day wear the crown, the baby will start out life wearing just a humble name tag inscribed with the name “Baby Cambridge”.