The Duke and Duchess of Cambridge - who are considered celebrities as much as royals - face an almost unparalleled level of media scrutiny with global interest in the couple unsated by their regular royal engagements.

William is known to value his privacy, and he and his wife Kate hope to give their young son George and his sibling - due at the end of April - a "normal" life and shield them from media intrusion.

William's relationship with the press has been shaped by what happened to his mother Princess Diana, said royal historian Hugo Vickers. Diana was hounded by the paparazzi and died in a car crash in Paris in 1997.

"I think Prince William has a great number of reasons for disliking the media in general, most particularly when you think what they did to his mother, the Princess of Wales, and I think he's always had, and I completely understand that, you know, a very strong awareness of what they are capable of doing," he said.

Previous generations of young royals, like William's father Prince Charles, were able to grow up out of the glare of the media spotlight.

And even when William and his younger brother Harry were children, 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.

But the expansion of the modern media and a never-ending news cycle means there is now an almost insatiable demand for images of the prominent royals.

"Probably the biggest difficulty the royal family has in fulfilling its role these days is the fact that there is a sort of 24/7 global media hungry for news in a way that wasn't when for example Prince Charles was growing up. That wasn't the case at all, I mean they were left in peace and people were much more deferential," said Vickers.

The British media is still reeling from recent phone hacking scandals and an inquiry into press regulation.

The chastened industry does not currently have the appetite to defy the royal family wishes and print unsanctioned photographs.

There now exists an uneasy truce between the British newspapers and the Duke and Duchess of Cambridge, but this does not apply in the rest of the world.

In 2012 when French magazine Closer printed grainy topless photos of Kate on holiday in France, William was furious.

More recently two paparazzi photographers were reported to have pursued Prince George and his nanny in a London park.

While William has not been afraid to take legal action against those who he considers to have breached his family's privacy, some say ultimately he can't win.

"When photographs of Kate have emerged that he doesn't approve of he is very protective of his family and you can see he very much doesn't like not to be able to control a scenario. He doesn't shrug it off. He very much fights for his family and I think that is commendable but obviously a problem for him because he can't control the press I mean it's impossible," said royal author Claudia Joseph, whose latest book on the couple is 'William and Kate's Britain'.

As royal photographer for Britain's leading tabloid newspaper The Sun, Arthur Edwards has spent more than three decades photographing the royal family. He said the relationship between the press and William could be better.

"It's not great, it's not great. He was determined to stop his wife and child being tormented by paparazzi. It hasn't quite worked but it's almost worked where there's not pictures published here; the disadvantage of that is there are pictures taken and they're appearing in France and America and Germany and so the Germans, the Americans and the French all know what George looks like but we don't," said Edwards.

He said the birth of the Duke and Duchess of Cambridge's second baby could provide an ideal opportunity for William to easily give the media what they want and hopes he will use the hospital steps for an endearing photo moment.

"We've got this opportunity coming up when Catherine goes into hospital obviously. If it's anything like when Princess Diana went in to have Harry the first visitor was the Prince of Wales with William walking up the step now if we can get that going in and out that would be nice for a start," he added.

"They are the hottest couple in the world now and they've got little George who one day will be a king, King George, but he is being very well protected. And I can see why William's doing that, I understand why but I think you know as a very privileged member of the royal family he should bear in mind that the public, the great British public would like to see more pictures," said Edwards.

But Joseph said William and Kate are likely to continue to try and keep their children behind-the-scenes as they go about their royal duties.

"We will meet him or her obviously at staged photo-calls, the christening, first birthday, that type of event but on the other hand most of the time they will keep the children out of the public eye," said Joseph.

So sanctioned scenes like when young George joined his parents on an official engagement at a Sydney zoo look set to remain a rarity as William and Kate continue the difficult task of maintaining a private family life while at the same time fulfilling their role as the world's most fascinating royal couple.