Britain's Prince William and Kate, Duchess of Cambridge and their newborn baby princess, pose for the media as they leave St. Mary's Hospital's exclusive Lindo Wing, London, Saturday, May 2, 2015. Kate, the Duchess of Cambridge, gave birth to a baby girl on Saturday morning.

Image Credit: AP Photo/Kirsty Wigglesworth

LONDON - From Prince Charles to the bettors at the corner store, everyone in Britain was hoping for a girl.

The Duchess of Cambridge delighted her nation and royal enthusiasts around the world Saturday by delivering one such princess. The royal birth was greeted with cheers and elated cries of "Hip, hip, hooray!" outside St. Mary's Hospital, where fans and the world's media have waited for days in central London.

The baby — Prince William and Kate's second child — was born Saturday morning and weighed 8 pounds 3 ounces (3.7 kilograms), officials said. She is fourth in line to the throne, and the fifth great-grandchild of Queen Elizabeth II, 89.

It may be a day or two before the world knows what to call her. When Prince George, her older brother, was born in 2013, royal officials waited two days before announcing his name.

Britain hasn't welcomed a princess born this high up the line of succession for decades. Speculation about the new royal's name has been frenetic, and all the top bets for the baby's name have been for girls: Alice and Charlotte are the clear favourites, followed by Elizabeth, Victoria and Diana — all names with strong royal connections.

Royal children are usually given several names — the baby's brother, for example, was christened George Alexander Louis — so the princess's name could incorporate more than one of those guesses.

Anticipation had been building for weeks after Kate, 33, told a well-wisher she was due around late April. Still, journalists were caught slightly off guard when she delivered barely three hours after checking into the hospital at dawn Saturday.

Both mother and infant were doing well, officials said, adding that senior royals "are delighted with the news." The queen marked the occasion by wearing a pink ensemble while carrying out an official engagement in North Yorkshire, 250 miles (400 kilometres) north of London.

William, who was present at the birth, emerged briefly to bring young George to the hospital to meet his baby sister. William told reporters he was "very happy," and George, cradled in his father's arms, dutifully waved to the adoring crowd.

Cheers and chants of "Princess! Princess!" rang out from the hundreds of well-wishers and tourists gathered outside the palace and the hospital as soon as the news was announced. One fan who had camped out outside the hospital for days danced with joy.

"I'm top of the world," said royal camper Terry Hutt, 80, decked out in patriotic Union Jack gear. He did not expect the birth to happen as soon as it did, but said: "Babies come when they're ready."

"If Diana was here, she'd be very, very proud," he added, referring to the late Princess Diana, William's mother.

The news was announced on social media sites like Twitter as well as by a traditional bulletin on a gilded easel in front of Buckingham Palace — a practice that dates to 1837.

A town crier in an elaborate costume — with no official connection to the royal family — shouted out the news at the hospital's door, clanging his bell to welcome the new royal.

"May our princess be long-lived, happy and glorious," said Tony Appleton, reading from a scroll in a booming voice.

Britain's Prince William and his son Prince George wave as they return to St. Mary's Hospital's exclusive Lindo Wing, London, Saturday, May 2, 2015. William's wife, Kate, the Duchess of Cambridge, gave birth to a baby girl on Saturday morning.

Image Credit: AP Photo/Kirsty Wigglesworth

Britain's political leaders — facing a hard-fought general election in just five days — rushed to congratulate the couple on the baby. Well wishes also poured in from the rest of the world, especially from Commonwealth countries like Canada and Australia.

At 21 months, George is third in line to the throne, after his grandfather Prince Charles and his dad William. The newborn princess becomes the fourth in line, bumping Uncle Harry to fifth.

The last princess born so close to the throne was Princess Anne, the queen's second child, in 1950. Princesses Beatrice and Eugenie, the daughters of Prince Andrew and Sarah Ferguson, were fifth and sixth in line at the time of their birth.

Thanks to a recent change in the law, the new princess will hold her place in the line of succession that for centuries had put boys ahead of their sisters. That means no younger brother will be able to overtake the new princess in the order of preference to inherit the throne.

Nonetheless, the princess probably doesn't have to worry about one day becoming queen. Royal succession rules dictate that the throne always passes to the eldest child. Younger siblings only get to step up to the job in rare circumstances — in case of an illness, death, or abdication.

The birth of their second child marks a new phase for William and Kate, who wed in a lavish ceremony at Westminster Abbey in April 2011.

The royal couple is expected to spend more time in their country digs, a 10-room brick-faced mansion known as Anmer Hall on the queen's estate in Sandringham, 120 miles (190 kilometres) north of London. Their apartment at Kensington Palace in central London, where much of their staff is based, will still remain their official home, officials say.

Anmer Hall is also better located for William's new role as a pilot for Bond Air Services, a helicopter operator that works with the East Anglian Air Ambulance service. He will work with doctors responding to emergencies ranging from road accidents to heart attacks.

Royal fans and well wishers react after Kensington Palace announced that Kate, the Duchess of Cambridge, had given birth to a girl, outside the Lindo Wing of St. Mary's Hospital, London, Saturday, May 2, 2015. Kensington Palace said in a brief statement that Prince William's wife "was safely delivered of a daughter" at 8:34 a.m. London time (0734 GMT) at central London's St. Mary's Hospital.

Image Credit: Daniel Leal-Olivas/PA via AP

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News from © The Associated Press, 2015