Big 30 for Kate

London - Catherine, Duchess of Cambridge, turns 30 on Monday after a near-faultless nine months of low-key royal engagements as she makes a gentle entrance into royal life alongside her husband Prince William.

The tabloids are full of rumours that William's party-loving brother Prince Harry and Catherine's high-profile younger sister Pippa Middleton are preparing a birthday party for the woman who will one day be queen.

But the royal family insists the occasion will be "low-key and private".

Regardless of the glitz or otherwise of the party, as she enters her fourth decade the former commoner Kate Middleton - most Britons still call her simply "Kate" - has already become a global icon.

Her wedding to the second-in-line to the throne last April was watched by an estimated two billion TV viewers and her face has adorned millions of magazine covers.

Clothes become best-sellers

Every one of her outfits is pored over and the clothes invariably become instant best-sellers.

Meanwhile, celebrity magazines scrutinise every photograph looking for evidence of a baby bump, but she is not pregnant yet, and the pressure will inevitably build from a hungry press as time goes on.

Catherine lives far from the bright lights and long lenses of London in Anglesey, north Wales, where William is training to be a Royal Air Force rescue pilot, and her public appearances are infrequent and carefully controlled.

As BBC royal correspondent Peter Hunt said: "She is, like Prince William, still tiptoeing towards her destiny."

Since the wedding, she has performed just 15 or so official engagements in Britain and a tour with William of Canada and California - a tiny number of appearances compared to other members of the royal family.

If she is rarely seen, she is heard even less. Catherine does not, yet, make speeches.

Happy to chat

Yet she enjoys huge popularity and those members of the public who have met her report that she is happy to chat and say that the daughter of a former pilot and flight assistant is without airs and graces.

When she made her first appearance with the royal family at their traditional Christmas Day church service, there was no doubt that Catherine, in a plum-coloured coat and hat, was the one the crowd had come to see.

This month, following royal tradition, she announced which charities she will support, and made a commitment to become a volunteer scout leader, mainly near to her Anglesey base.

She will be associated with just four charities - the queen is patron of 600. Catherine will link up with a group which helps wayward children through art and a charity helping former drug addicts to put their lives back on track.

She has ever so gradually started to follow the path of William's late mother Diana, who championed the plight of Aids patients and landmine victims among many causes.

Needs to take risks

In a slightly barbed comment on Catherine's charity commitments, The Independent said it is "an arrangement to suit everyone".

"The charities get cash and visibility. The princess gains a public persona - much-needed, as it happens, since there has been a growing sense over the past few months, that, beyond the trim figure and the pearly-toothed smile, the new member of the royal family is ever so slightly dull."

Yet such digs are few and far between, and as she turns 30 Catherine enjoys an overwhelmingly positive press, with newspapers also perhaps treading carefully after their ceaseless pursuit of Diana.

Robert Jobson, the author of William and Kate: The Love Story, told AFP that she should resist pressure to change the personality which first attracted William when they were students together at university in Scotland.

"Everyone's got great expectations but it's important for Kate, if she's going to be accepted and popular, to be herself," he said.

"You can't be a media-managed perfect princess, there is no such thing, you can't create the image of a princess on a computer screen and make it absolutely how it has to be.

"You have to take risks, you have to show your personality. At present, she hasn't really had the opportunity to do that."