LONDON » A crowd cheered, hundreds of cameras clicked and an image of familial perfection was beamed around the world.

Prince William, his wife Kate and their infant son, the Prince of Cambridge, emerged today from London’s St. Mary’s Hospital to start a new chapter in their lives — capping a remarkable turnaround for a monarchy that had ended the 20th century at a low point of popularity.

The outpouring of public and official enthusiasm — including artillery salutes, marching bands and landmarks illuminated blue for the royal baby boy — showed that Britain’s royal family is back in its subjects’ affections, especially now that it has an adorable infant heir, third in line to the throne, who could be king into the 22nd century.

"It’s had its ups and downs in public opinion," said veteran royal commentator Dickie Arbiter. "But in the last 20 years it has had more ups than downs."

Pictures of William, Kate and their baby, whose given names have yet to be announced, echoed a similar image taken 31 years ago, when Prince Charles and Princess Diana left the same hospital with baby William in their arms.

William and Kate looked much more relaxed than the awkward Charles and Diana, and within a few years the older couple’s image of regal domestic bliss had been comprehensively trashed.

By the late 1980s and early ’90s, the royal family was making headlines for all the wrong reasons. More often than not the stories were about marital troubles among the children of Queen Elizabeth II, especially for Charles and his unhappy wife Diana.

The divorce or separation of three of the monarch’s four children in 1992, along with a damaging fire at Windsor Castle, led the queen — in a rare admission of private feeling — to dub it a horrible year, her "annus horribilis."

Then in 1997 came Diana’s death in a car crash — a personal tragedy that also became a crisis for the monarchy. Warm, glamorous and unhappy in her royal marriage, Diana had — in the eyes of many — been badly treated by the royal "Firm." The queen and other senior royals, caught by surprise by an outpouring of public grief at her death, appeared cold and remote.

But that image has since been transformed, partly because of the dignified endurance of Queen Elizabeth II, now in her 62nd year on the throne. At 87, she is the only monarch most Britons have ever known, a reassuring presence at the heart of national life who has in recent years given public hints of her private sense of humor — even agreeing to appear alongside Daniel Craig’s James Bond in a short film for the 2012 Olympics opening ceremony.

If the queen gives the family gravitas, the emergence of an attractive young generation that includes William, his soldier-socialite brother Prince Harry and the glamorous, middle-class Kate gives it celebrity.

William’s work as a search-and-rescue helicopter pilot, Harry’s army service in Afghanistan, and Kate’s girl-next-door charm have all proved assets. Even seeming faux pas such as Harry’s strip-billiards antics in Las Vegas have done little but burnish his popularity.

William and Kate’s Westminster Abbey wedding in 2011 was an extravaganza of pageantry that brought thousands into the streets for celebratory parties.

The baby adds a new layer of stability to help the institution thrive for another generation. For the first time since the 19th-century reign of Queen Victoria, Britain has three generations of living heirs to the throne — Prince Charles, William and his baby son.

Through Kate, the future king also has a dose of non-royal blood. Her family, although affluent, comes from an ordinary, middle-class background.

"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."

Diana was a commoner in the strict sense that she was not royal, but unlike Kate she came from an aristocratic family.

The importance of that common thread was echoed by Pippa Rowe, head teacher at the primary school in Kate’s home village of Bucklebury, west of London.

"I think this will enable the children to have a real chance to connect with the monarch," she said. "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."

The cost of affection for the royal family, in our media-saturated times, is a hunger for intimacy. The young royals are global celebrities, and there is a vast demand for images and information about them from the world’s media.

William and Kate will struggle against that hunger as they try to give their son a normal childhood, as much as possible out of the spotlight.

Arbiter said William’s own childhood would help him give his son a balanced upbringing. William was educated alongside children from a wide variety of backgrounds, albeit at some of Britain’s ritziest private schools.

"I’m not going to use the word ‘common,’ but it was a well-rounded upbringing," Arbiter said.

"And, of course, his mother gave him the high street. He knew what it was all about to go to a movie or go into McDonald’s or a book store. He knew how to handle money, which is something older royals didn’t do. He will bring up his children in the way he was brought up, and probably with some new touches from Catherine."