Prince William's wife Kate was in labour in hospital on Monday as the world awaited the birth of a royal baby that will one day be heir to the British throne.
Catherine, Duchess of Cambridge, attends the National Review of Queen's Scouts at Windsor Castle on April 21, 2013. Prince William's wife Kate has been admitted to hospital in the early stages of labour as the world awaits the birth of a baby directly in line to inherit the British throne.
A global frenzy over the arrival of a new generation of British royalty reached fever pitch as the 31-year-old couple took up their plush London hospital suite for the birth.
The Duchess of Cambridge was admitted just after 6:00 am (0500 GMT), but nearly 12 hours later there was still no news for the hundreds of international media camped outside.
The baby will be third in line to the throne and in the direct line of succession after Queen Elizabeth II's eldest son and heir Prince Charles, and then his eldest son William.
"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," Kensington Palace said in a statement.
"Things are progressing as normal," a spokesman said.
The queen's return to Buckingham Palace from Windsor Castle outside London on Monday afternoon prompted a brief flurry of speculation that the baby had been born, but it then died down.
The birth is later than widely expected, adding to the sense of anticipation that has built up ever since William, whose mother Diana died in a Paris car crash in 1997, and the former Kate Middleton married with huge fanfare in April 2011.
Kate has said the couple the couple does not know the sex of the baby.
But if it is a girl, then new succession laws being brought in across the 16 Commonwealth realms would mean that she could no longer be overtaken by any future younger brothers.
William, at his wife's bedside, has been on annual leave and will take two weeks' paternity leave from his military job as a Royal Air Force search and rescue pilot.
The royal couple used a back entrance to the private Lindo Wing of St Mary's Hospital, arriving just after dawn and accompanied by thunder and lightning from a passing storm.
They were missed by the ranks of media from around the globe who have camped outside the hospital for three weeks.
The prince was born in the same hospital wing and media from across the globe are hoping for a repeat of the scene in 1982 when Charles and his first wife Diana brought out the baby to show him off to the world.
On the hottest day in Britain for seven years, a bustling media pack broadcast live updates around the world, while royal fanatics took their excitement to a new level.
"I'm so excited. Like in a washing machine. Never been so high!" said John Loughrey, who has slept outside the hospital for seven nights, wrapped in a British flag.
The new arrival will be head of state Queen Elizabeth's third great-grandchild, and a first grandchild for Charles.
It ensures that there are three generations of heirs to the crown of the United Kingdom of England, Wales, Scotland and Northern Ireland -- a nuclear-armed UN Security Council permanent member and the world's sixth biggest economy.
The birth is set to be formally announced when a document signed by the doctors is placed on a golden easel in the palace forecourt.
Charles, the current heir, was visiting York in northern England, where members of the public shouted "Congratulations!".
Smiling, he replied: "Do you know something I don't?"
Charles, who turns 65 in November, joked: "I'm very grateful indeed for the kind wishes for my rather slowly-approaching grandfatherhood."
Prime Minister David Cameron sent his best wishes to the couple and said he was confident the laws would be pushed through.
"A very exciting occasion and the whole country is excited with them. So everyone's hoping for the best," he said.
The baby's title will be His/Her Royal Highness Prince/Princess (name) of Cambridge.
The pregnancy was announced in December when Kate was admitted to hospital with severe morning sickness.
At the Lindo Wing, a standard room and normal delivery -- which Kate is hoping for -- costs pound sterling4,965 ($7,600, 5,800 euros) for the first 24 hours, plus consultants' fees which can reach around pound sterling6,000.
The duchess is being tended by a top medical team led by the queen's gynaecologist Alan Farthing and his predecessor Marcus Setchell.
On the pavement opposite the hospital entrance, around 30 presenters lined up in a row delivering live broadcasts and clips, with photographers and journalists filling out the scene.
Yang Shanshan, from China's CCTV, told AFP: "We've been waiting for this for 10 days now. It was a long wait."
Crowds were also gathering outside Buckingham Palace.
Outside the palace, Josh Killoren from Melbourne told AFP: "I'm hoping it's a boy. I'm sick of seeing a girl on the side of our coins."
Jane Ku from Singapore said: "We've been waiting for the baby for days! We're going to buy all the baby souvenirs."
There has been a betting frenzy on the name of the royal newborn with bookmakers favouring a girl named Alexandra or Charlotte.
Other favourites are Diana, Elizabeth and Victoria, with George and James the top boys' names.