The latest addition to the royal family has been named Prince George Alexander Louis, but where did the Prince get his names?
The Duke and Duchess of Cambridge have named their son George Alexander Louis, Kensington Palace said.
With the imminent arrival of the Duke and Duchess of Cambridge's firstborn here are some of the more unusual facts about royal babies.
Prince Charles was given a gift for the upcoming addition to the royal family during his visit to York.
As he accepted the gift, Charles said the baby "hasn't quite appeared yet".
Alex Dickinson said her son Freddie "thinks [the baby] is going to appear in six hours time", to which the Prince replied, "You might be right".
The Prince of Wales arrived at the National Railway Museum in York by steam train as he started his tow-day tour of Yorkshire. As he awaited news of the birth of his first grandchild, Charles stepped off the Royal Carriage to applause and cheers from the waiting crowd.
The carriage was pulled into the museum, by Bittern, the sister engine of Mallard which celebrated 75 years as the world's fastest steam train earlier this month.
Whoop whoop the royal baby is comming
As the news breaks that the Duchess of Cambridge has gone into Labour, Prince Charles in expected in York. He is due to visit the Railway Museum to mark the 75th anniversary of the Mallard Locomotive. The Prince of Wales will then go to York Minster
- The baby will be the Duke and Duchess of Cambridge's first child
- William and Kate will have been married for two years when the baby is born
- He or she will be third in line to the throne and the Queen's third great-grandchild
- Prince Harry will be bumped down to fourth in line to the throne
- The baby will one day be head of state of 16 countries
- William and Kate will both be 31 when the baby is born
- Royal births are celebrated with a 41-gun salute
- If the baby follows the Prince of Wales and William on to the throne, he or she will be the 43rd monarch since William the Conqueror in 1066
- It costs £6,265 for a one night stay and delivery package at the private Lindo wing including a suite of two rooms, but this excludes consultant's fees
- The Duchy of Cornwall landed estate - which will privately fund the baby's future as an heir apparent - has a yearly income of £18.3 million.
The Lindo Wing at St Mary's Hospital in Paddington, London, where the Duchess of Cambridge is due to give birth, is an exclusive private facility offering "bespoke care packages".
Fully refurbished in 2012, the wing describes itself as having offered "leading private obstetric and neonatal care for 60 years".
It has private en suite rooms designed to provide "comfort and privacy". Deluxe rooms and suites are also available.
A normal delivery package including a one-night stay costs £4,965, with an extra night in a deluxe room costing £1,050, plus consultant's fees which can come to around £6,000, depending on the care required, meaning a two-night stay can cost more than £12,000.
A suite of two rooms, with one used as a living room, costs £6,265 for a one-night stay with normal delivery and £2,200 for each extra night, meaning a two-night stay, with consultant fees of an estimated £6,000, would cost around £14,465.
Each room has a satellite TV with major international channels, a radio, a safe, a bedside phone and a fridge.
The expectant mother and her visitors can access the internet via wifi and there is a choice of a daily newspaper delivered to the room each morning. Toiletries are also provided.
All meals are freshly prepared in a dedicated kitchen and tea and coffee is provided for mothers and guests throughout the day.
The wing also offers a "comprehensive wine list should you wish to enjoy a glass of Champagne and toast your baby's arrival".
The arrival of the Duke and Duchess of Cambridge's firstborn will be announced by the age-old custom of placing a proclamation of royal birth behind the iron railings of Buckingham Palace.
The notice will begin its journey at the Lindo wing of St Mary's Hospital in Paddington, London, where Kate's baby is being delivered.
The brief bulletin, on headed Palace notepaper, confirms the sex of the baby but usually gives little else away other than that the baby has been "safely delivered" and perhaps the weight.
It used to be hand-written but is now mostly typed and will be signed by the Queen's former gynaecologist Marcus Setchell, who is leading the medical team looking after the Duchess.
Placed in a foolscap-sized dark wooden frame, it will be set on an ornate easel behind the railings, just to the side of the front gates of the Queen's London home for members of the public to read.
But the notice will not be put in place until the monarch and senior members of the Royal Family have been told of the new addition to their family.