LONDON » Prince William, Kate and their baby boy were spending their first full day as a family today inside a London hospital, thanking staff for their care but making well-wishers wait for a first glimpse of the royal heir.

As celebratory lights, gun salutes and other tributes were unleashed in Britain and abroad, William thanked staff at St. Mary’s Hospital "for the tremendous care the three of us have received."

"We know it has been a very busy period for the hospital and we would like to thank everyone — staff, patients and visitors — for their understanding during this time," he said in a statement.

The couple’s Kensington Palace office said Kate, the Duchess of Cambridge, had given birth to the 8 pound, 6 ounce (3.8 kilogram) baby boy at 4:24 p.m. Monday, triggering an impromptu party outside Buckingham Palace and in front of the hospital’s private Lindo Wing.

The palace said today that "mother, son and father are all doing well this morning."

The new family was expected to remain in the hospital until this evening or Wednesday morning.

In the meantime the infant’s appearance — and his name — remain a royal mystery.

Tourists and well-wishers flocked to Buckingham Palace today, lining up outside the gates to take pictures of the golden easel on which, in keeping with royal tradition, the birth announcement was displayed.

"This was a great event — yet again our royal family is bringing everyone together," said 27-year-old David Wills, who took a two-mile detour on his run to work to pass the palace. "I kind of feel as though I am seeing part of history here today."

A band of scarlet-clad guardsman at the palace delighted onlookers with a rendition of the song "Congratulations."

Other celebrations today included gun salutes by royal artillery companies to honor the birth and the ringing of bells at London’s Westminster Abbey.

Halfway around the world, royalist group Monarchy New Zealand said it had organized a national light show, with 40 buildings across the islands lit up in blue to commemorate the royal birth, including Sky Tower in Auckland, the airport in Christchurch, and Larnach Castle in the South Island city of Dunedin. A similar lighting ceremony took place in Canada; Peace Tower and Parliament buildings in the capital, Ottawa, were bathed in blue light, as was CN Tower in Toronto.

The baby isn’t even a day old — and may not be named for days or even weeks — but he already has a building dedicated to him.

Australian Prime Minister Kevin Rudd said an enclosure at Sydney’s Taronga Park Zoo would be named after the prince as part of a gift from Australia. The government would donate 10,000 Australian dollars ($9,300) on the young prince’s behalf toward a research project at the zoo to save the endangered bilby, a rabbit-like marsupial whose numbers are dwindling in the wild.

British media joined in the celebration, with many newspapers printing souvenir editions.

"It’s a Boy!" was splashed across many front pages, while Britain’s top-selling The Sun newspaper temporarily changed its name to "The Son" in honor of the tiny monarch-in-waiting.

Beyond the newsstands, the birth of the royal baby was welcome news in a country where polls show the monarchy is as popular as any time in recent history. In the Yorkshire village of Bugthorpe — which Prince Charles was visiting as part of a tour through northern England — the baby was on everyone’s lips.

"Morning Granddad," said local resident Robert Barrett, which drew a chuckle from the prince.

Back in London, there was a healthy interest in the baby’s name, combined with a note of concern for his future.

"I hope the child is given the opportunity to have a normal childhood," said Julie Warren, a 70-year-old retired schoolteacher waiting for her grandson outside one of the capital’s subway stations.

The birth caps a resurgence in popularity for Britain’s monarchy, whose members have evolved, over several decades of social and technological change, from distant figures to characters in a well-loved national soap opera.

The institution reached a popular nadir after the death of Princess Diana in a car crash in 1997. Diana had been popular, glamorous and — in the eyes of many — badly treated by the royal "Firm."

But the dignified endurance of Queen Elizabeth II — now in her 62nd year on the throne — and the emergence of an attractive young generation that includes William, his soldier-socialite brother Prince Harry and the glamorous, middle-class Kate has been a breath of fresh air for the monarchy.

The baby, born to a prince and a commoner, looks set to help the institution thrive for another generation.

"I think this baby is hugely significant for the future of the monarchy," said Kate’s biographer, Claudia Joseph. "It is the first future king for 350 years to have such an unusual family tree. Not since Queen Mary II has the offspring of a ‘commoner’ been an heir to the throne."

That view was echoed by Pippa Rowe, head teacher at the primary school in Kate’s home village of Bucklebury, west of London.

"The children have been very excited about the birth — fizzing is the word I would use," she said. "It’s all the talk in the playground.

"I think this will enable the children to have a real chance to connect with the monarchy. They learn about kings and queens but we are going to have a real live prince with one set of grandparents living down the road."

For some, though, it was all a bit much.

"It’s a baby, nothing else," said Tom Ashton, a 42-year-old exterminator on his way to work. "It’s not going to mean anything to my life."

Associated Press writers Gregory Katz, Paisley Dodds, and Maria Cheng in London, Rod McGuirk in Canberra, and Kristen Gelineau in Sydney contributed to this report.