The Duchess of Cambridge has been admitted to St Mary's Hospital in west London in the early stages of labour, Kensington Palace have announced.
'The Great Kate Wait', as many journalists referred to the final stages of the Duchess' pregnancy, is finally over after a brief statement was released at 7.30am. The palace confirmed that the Duchess was “doing well” and the birth was “progressing normally.”
The statement read: "Her Royal Highness The Duchess of Cambridge has been admitted this morning to St Mary's Hospital, Paddington, London, in the early stages of labour.
"The Duchess travelled by car from Kensington Palace to the Lindo Wing at St Mary's Hospital with The Duke of Cambridge."
The Duke and Duchess were driven without a police escort before Kate was admitted to the Lindo Wing just before 6am on Monday, their spokesperson added.
"Things are progressing as normal," he said.
The Queen has now arrived at Buckingham Palace as Prince William waits by his wife's bedside.
St Mary's Hospital said they were "exceptionally proud" that a future heir to the throne will be born there, adding that Kate will be treated by expert consultants.
“As Kensington Palace have confirmed, HRH the Duchess of Cambridge was admitted to the Lindo Wing at St Mary’s Hospital earlier today, having entered the final stages of her pregnancy.
"During her stay at the hospital, the Duchess is being cared for by an expert team of consultants and midwives. It goes without saying that the whole trust wishes her well and we are exceptionally proud that the Duke and Duchess of Cambridge have chosen to have their baby here.”
Marcus Setchell, the Queen's gynaecologist for two decades, is in charge of the care Kate will receive and helped save the lives of the Countess of Wessex and her eldest child Lady Louise Mountbatten-Windsor in 2003.
He became the royal household's gynaecologist in September 2008 and Kate's baby is his first high-profile royal birth.
The Duke and his younger brother Prince Harry were born in the same hospital wing and the Prince and Princess of Wales famously posed on the building's steps in 1982 holding baby William.
Prime Minister David Cameron sent his "best wishes" to the Duke and Duchess of Cambridge, describing the occasion as "very exciting" for the pair. However, it was business as usual for The Prince of Wales, who said he had heard "absolutely nothing at the moment", when asked about the birth by Sky News.
"We're waiting," he added, during a visit to the National Railway Museum in York on Monday.
Members of the public gathered outside to greet the Prince of Wales and shouted “congratulations” as he left the glaziers' workshops. He walked over to one woman and joked: “Do you know something I don't?”
Another well-wisher, John Dowson, from York, shouted: “It's triplets”, prompting a chuckling Charles to come over to him for a word.
Bookmakers are currently favouring the name 'Alexandra' for the third-in-line to the throne, as many have placed bets that the Duchess will give birth to a girl. George and James are popular monikers for those who think the new baby will be a boy.
Paddy Power reported £30,000 taken in bets within the first three hours of the announcement. Bets on the birth date have now been suspended. The betting store even opened bets on the colour of Pippa Middleton's dress if she visits the baby in hospital.
William is expected to take paternity leave from his job as an RAF search and rescue helicopter pilot, but it is not known how long the Duchess will take off from her royal duties to care for her first child.
The infant will be the Queen's third great-grandchild and is destined to be crowned monarch.
It will be the 43rd sovereign since William the Conqueror if, as expected, it follows reigns by Charles then William.
The Duke is known to want a daughter while the Duchess is hoping for a son.
When Kate met Guardsman Lee Wheeler, 29, during a St Patrick's Day parade in Aldershot, Hampshire, she told him she did not know the sex of her baby.
The soldier said: "I asked her 'Do you know if it's a girl or boy?', and she said 'Not yet'.
"She said 'I'd like to have a boy and William would like a girl'. That's always the way."
Recent changes to the rules of succession have now ensured that if the Duchess gives birth to a girl she will not be leapfrogged by a younger brother at a later date. Under the previous succession law, dating back to 1701, a male infant would succeed to the throne before a female child. The Succession to the Crown Act 2013 legislates that the sex of an infant in direct line to the throne no longer determines whether he or she wears the crown.
Twitter has now been flooded with excited tweets regarding the impending arrival of the royal baby. Former Deputy Prime Minister John Prescott took a more tongue-in-cheek approach to the news by tweeting: "Great to hear the Duchess of Cambridge has gone into labour. Is she an affiliated member?" The Archbishop of Canterbury also used social media to wish Kate well and tweeted: "My thoughts and prayers are with Kate on this enormously special day".
As the Duchess' due date has drawn closer the 'Great Kate Wait' hysteria has seen the worlds press camp outside St Mary's hospital for the birth. Newspapers have even set up cameras outside the hospital she was believed to have chosen to give birth in to create a live stream of action from outside on their websites.
Well-wishers from across the globe have now joined the media to gather in anticipation outside St Mary's gates as excitement reaches fever pitch.
Bookmakers have even seen bets placed on the infant's star sign. If born today, the child will be a Cancer under the Zodiac calendar, and if born tomorrow it will be a Leo.
There is a strong police presence around the immediate vicinity of the hospital. Two police officers are guarding the entrance to the Lindo wing.
Tina Harris, a lead midwife at De Montfort University warned that there may not be any news of an arrival until early this evening. "Labour can take anything from a few hours to a couple of days," she said, "especially for women having their first babies."
Additional reporting by PA