LONDON (AFP) – The weight of expectation on Britain's new royal baby is already huge but his father Prince William is ready to guide him in treading the fine line between duty and a private life.
As the eldest son of Prince Charles and the late Diana, Princess of Wales, William knew from an early age his role as second in line to the throne, just as his heir will soon learn what is expected of him.
Yet despite the responsibilities of his birth, and the trauma of losing his mother aged just 15 in a car crash, the Duke of Cambridge has managed to balance royal ribbon-cutting with a military career and a personal life of his own choosing.
The 31-year-old and his wife Catherine are expected to be hands-on parents, reflecting their own warm upbringings, and to fiercely protect the child's privacy as they have their own.
And while certain things will be expected of the new royal heir, William will likely battle hard to give him the same semblance of normality that he himself has enjoyed.
The prince is a Royal Air Force (RAF) search-and-rescue helicopter pilot in Wales, a job that gives him excitement and purpose as he waits potentially decades for the throne.
It also gave him the space to enjoy the first few years of marriage alone with his wife, the former Kate Middleton.
Their marriage in April 2011 was a global event, but William delayed tying the knot for almost a decade to ensure the match was right, just as the couple then waited two years before starting a family.
Aides say he has always fought to do things his way.
"You have to be slightly stubborn because everybody wants you for one reason or another," William once said.
William Arthur Philip Louis was born on June 21, 1982 into a life of wealth and privilege, although Diana ensured he and his younger brother Harry did not suffer the rather cold upbringing endured by their father.
She showered the boys with affection and, although they were brought up in a palace by nannies, took them on official trips and to charity events to see how ordinary people lived.
William has Diana's gift for engaging with people, and is an assured and often amusing public speaker.
-- 'Sense of self-protection' --
To the outside world, he appears remarkably well-adjusted, a small miracle given his parents' acrimonious divorce and Diana's sudden death in Paris in 1997.
William was drawn into the couple's power games and was his mother's confidante, pushing tissues under the bathroom door as she sat sobbing inside.
But he emerged with a warm memory of Diana and a good relationship with Charles, as well as with what one aide said was an "innate sense of self-protection".
William's early hatred of the media -- which he believed harassed his mother -- has given way to grudging acceptance, but he tries not to give them too much to write about.
He was widely criticised in 2007 when he borrowed an RAF helicopter to fly to a stag weekend, while a few stories have emerged of his student drinking and "roving eye".
Pictures of him dancing with a mystery blonde in a nightclub contributed to a brief split from Kate, whom he had met at university several years previously.
But broadly William has kept his image and his interests clean, from sport -- he is a fan of Aston Villa football club and has played everything from rugby to polo -- to indulging his passion for motorbikes.
He has benefited from long spells of time out of the public eye, spending much of his childhood at boarding school, including the elite Eton College.
And a deal with the media to leave him alone at the University of St Andrews in Scotland resulted in four years of unparallelled freedom.
William graduated with a degree in geography and joined the army, a well-trodden career for a prince who will one day be commander-in-chief.
He wanted to serve with British troops in Afghanistan, like Prince Harry, but it was considered far too dangerous for a future king.
William instead spent time in all three branches of the military before settling on search and rescue, although he must decide this summer what to do after his RAF job comes to an end.
Fatherhood brings new responsibilities, and with Queen Elizabeth II, at age 87, scaling back her duties, William may have to step up. It remains to be seen how long he can balance his two lives.