'Queen Catherine' Kate Middleton

If all things go to plan, her name will be etched on mugs, plates and the pages of history.

So for Kate Middleton, it's very important that we all get it right.

The royal girlfriend has apparently asked that everyone call her Catherine, a name with a much more formal ring and a queenly history.

Some say that Miss Middleton, 26, is trying to give herself a more formal image, befitting a young woman who could one day be married to a king.

But others point out that she has never been called Kate in private  -  not by her family, friends, schoolmates or university pals.

The news comes amid mounting speculation that Miss Middleton and Prince William are close to becoming engaged.

A close friend said yesterday: "Everyone knows it's about to happen with Kate and William but we were a little surprised about the request to call her Catherine.

"There's a distinct feeling that she has started to become very aware of her position."

The press has been blamed for giving Catherine Elizabeth Middleton her nickname, when her relationship with the prince was confirmed in 2004.

"No one ever referred to her as Kate  -  ever," says a former classmate. "It doesn't irritate her, even when the photographers shout her name out. She's not so precious as to correct them.

The couple are holidaying on the romantic tropical island of Mustique with speculation William could use the trip to propose

"But her family and close friends have always called her Catherine and that's the way she prefers it."

One source joked: "It's certainly more queenly."

But one former contemporary has been less impressed with her old classmate, saying yesterday: "At school, Catherine was really jolly hockey sticks, fun and jump-in-the-dirt  -  a great girl," she said.

"Now she seems much more concerned about her image - who she is with, who she is talking to and the like. That's what I have found a bit off."

Luxury: Alumbrera, the villa where Prince William and Kate Middleton are thought be staying

Miss Middleton is currently on holiday with Prince William on the romantic Caribbean island of Mustique, adding fire to the engagement speculation.

Even bookmakers have stopped taking bets on the likelihood of William proposing.

The couple are staying at the exclusive five-bedroom £1,785 a night Villa Alumbrera  -  the most opulent mansion on the island.

Yesterday, asked on the phone if they were having a fun time, Miss Middleton replied "Yes" but she would not comment on the engagement rumours.

Official: Ms Middleton with Prince Harry's girlfriend Chelsy Davy at Peter Phillips' wedding. Prince William asked her to represent him because he could not attend

She said: "I'm terribly sorry but I will not talk about that. I am truly sorry but please excuse me."

If Prince William, 25, is planning a proposal he could not have selected a more exclusive resort as a backdrop.

Owned by the widow of Swedish mining tycoon Adolf Lundin, their lavish rented villa is perched on a cliff.

It boasts every conceivable modern convenience as well as floor-to-ceiling windows framing views of the Atlantic Ocean.

The official website says: "Mustique Island has long been a favourite for honeymoon couples as it provides both an intimate villa experience as well as a romantic island lifestyle."

The villa is booked until May 28 when Prince William is due to return to the UK for a three-month attachment with the Royal Navy.

The couple met while they were students at St Andrews University, Scotland and despite a brief split last year they have been together for around four years.

Their wedding has become the most eagerly awaited royal union since the marriage of Prince Charles to Princess Diana in 1981.

Miss Middleton's failure to find a career, despite flirting with photography and working for a short while in the fashion business, is seen by many as a clear indication she is preparing for life as a princess.

Royal experts say that she has, through a series of engagements and functions, been gradually groomed for a life in the Royal Family.