LONDON (AFP) - The world's media have been camped for days outside the London hospital where Prince William's wife Catherine will give birth, but the royal couple are expected to tightly control access to the new heir to the throne.

Once the newborn is presented to the public, the little prince or princess is likely to be kept out of the spotlight for weeks, if not months, experts say.

For all that the royals have complained about media intrusion in the past, notably following the death of William's mother Diana, they now successfully manage their exposure through a slick PR operation.

"Control over access to the baby and to their family absolutely lies in the hands of William and Kate," said Patrick Jephson, former chief of staff to Princess Diana.

"There will be unprecedented media interest in this baby and that will continue for the rest of its life," he said.

"But the birth itself - there will be a brief period when the baby is shown to the public, and I expect for some weeks thereafter it will disappear." Valentine Low, royal correspondent of The Times, agrees the baby will start life with a low profile.

"William and Kate will be desperate to keep as much as privacy as they can," he said. Prince William's relationship with the media is far better now than it was when his mother died in 1997, but he remains protective of his privacy.

He and his younger brother Prince Harry developed a deep dislike of the press after witnessing the relentless pursuit of Princess Diana by the paparazzi.

Her death paved the way however for a new relationship between the royals and the British media, who agreed to leave the princes alone while they grew up.

This deal continued through university, where Prince William was free to woo Catherine without the glare of publicity.

Since then the royal family has been active in protecting the couple and particularly Catherine, who has proved almost as irresistible as Princess Diana was to the world's press.

Buckingham Palace has sent warning letters to editors and last year launched legal proceedings over the publication of topless photographs of Catherine in several European magazines.

Those pictures never appeared in Britain, where the media has a vested interest in keeping on the good side of royal aides.

"The palace is very protective of their privacy and the mainstream media don't push it at the moment," Mr Low said.

However, he added: "There are those paparazzi and other people out there who will be desperate for pictures which will have international value." For them, the tax-funded royals are fair game - a view expressed by Ray Bellisario, a photographer who doggedly covered the family in the 1960s and 1970s.

"Let's get real - they love it. Without it, where the hell would they be?" he said.