From the moment the baby boy leaves hospital in the arms of his parents in front of an army of TV cameras and photographers, his life in the public eye begins and so does his parents' formidable battle to protect his privacy.
That will have become harder in recent years with the advent of modern phones which mean anyone can take a high-quality picture and beam it around the world instantly via social media.
"I'm sure William and Kate will be desperate to give their baby as similar an upbringing as they had, as much out of the public eye as possible," royal author Claudia Joseph told Reuters.
Kate, as the first "commoner" to marry a prince in close proximity to the throne in more than 350 years, naturally enjoyed an upbringing out of the limelight.
William and his younger brother Harry were able to grow up largely out of the media spotlight after Britain's press agreed not to intrude, with little snooping into their early years apart from special occasions such as their first day at school.
Their mother, the late Princess Diana, had been determined that they should realise life was not all palaces and servants, taking them on family outings such as to an amusement park where they queued for the rides with other visitors.
"Diana wanted William to experience life from all sorts of angles," Joseph said. "She took him to HIV clinics, and to homeless charities and that's perhaps why he is the rounded man he is today and I'm sure he's conscious of that.
"Kate will want to emulate the upbringing she had with her own parents because her family is so stable and close to each other."
MUDDY PUDDLE
Olga Powell, William's nanny who died last year and cared for him and Harry over a 15-year period which saw their parents divorce and the death of their mother, described how they were the same as any other children.
"If they saw a muddy puddle they wanted to jump in it and if there was something to climb, they wanted to climb it," Powell told her local newspaper shortly before William's glittering marriage to Kate in 2011.
"Their parents wanted them to have as ordinary a childhood as they could."
But just how "normal" can the childhood be of a future monarch and the first heir to be born for 31 years, especially one born to parents whose own childhood would be alien to an average Briton?
The baby was born with William at Kate's side on Monday and weighed 8lbs 6oz (3.8 kg).
Kate herself enjoyed a privileged upbringing, attending exclusive private schools before going to university in Scotland where she met William.
For his part, William went to school at Eton College, one of the country's top and most expensive establishments whose alumni include Prime Minister David Cameron.
But Joseph said the couple had eschewed a glitzy life of luxury since their marriage, living quietly near William's Royal Air Force base in north Wales with a house cleaner but no retinue of servants.
"The reality is they've been living in a cottage in Wales, going to the cinema, to the supermarket, and doing the things we all do. They cook and wash up for themselves," Joseph said.
"Obviously they had to do royal engagements but other times William and Kate have strived to maintain a normal life very much as they had an university."
Royal historian Hugo Vickers said the royal couple would want the same with their own child.
CURIOUS WORLD
"What we've seen with William and Kate is they lead as normal a life as they possibly can given the rather curious world in which they live," he told Reuters.
"You can be fairly certain that they will be very hands-on parents and they will be very anxious to give the child as normal an upbringing as possible.
"It will be possible for them to do it as long as the media respects their privacy which, unfortunately, there has been quite a lot of evidence they have not done so, even with William and Kate."
The House of Windsor is no stranger to intense public scrutiny and media fascination with the public disintegration of the marriage of Princess Diana and William's father, heir-to-the-throne Prince Charles, in the 1990s a prime example.
In the past, it was the prying long lenses of the media, such as those which captured grainy topless pictures of Kate on holiday in France last year, that were a concern.
For William and Kate, technological advances mean anyone with a phone can post a threat.
"The modern forms of media, be it Facebook, Twitter or whatever, are the biggest intrusions into anyone's private life but particularly if the person is a member of the royal family. It won't be easy to contain these things," Vickers said.
VEGAS PICTURES
William's younger brother Prince Harry has fallen victim to the modern camera phone with pictures of him partying naked in a private room while on holiday in Las Vegas beamed around the world in newspapers and on the internet.
Such intrusion and risk of betrayal is nothing new for the royals. Even the queen suffered personal details being publicised by a former nanny, Marion "Crawfie" Crawford who wrote a book about the upbringing of Elizabeth and her younger sister Margaret, to the fury of Buckingham Palace.
"That was perhaps worse than any kind of paparazzi lurking in the bushes at a chateau where Prince William and Kate were sunbathing with her topless, which caused such a fuss a few months ago," royal author Charles Mosley said.
A poll for London's Evening Standard newspaper last week found seven out of 10 Britons thought it was "impossible" for royal children to have a normal upbringing. Mosley said whatever Kate and William's hopes for privacy for their baby, it was a battle they would lose.
"How on earth can they have a normal childhood? This royal family is the most photographed media-interest attracting institution in the world," he said.
"Everything about it is under constant scrutiny. That is something there is no possible way of overcoming." -- REUTERS
