Princess Eugenie gets glam in Tatler photoshoot to mark her 18th birthday

In her earlier years, she was often seen in public dressed identically to her sister Beatrice.

But as she approaches her 18th birthday, Princess Eugenie is developing her own striking sense of style - even if it's not entirely original.

Her glossy beehive and gamine features elegantly echo Audrey Hepburn's classic look that entranced millions in movies such as Breakfast At Tiffany's.

Eugenie and older sister Beatrice - called ' The Yorkies' by friends - are very close

Eugenie, younger daughter of Prince Andrew and Sarah, Duchess of York, highlighted her Hepburnesque qualities in a Tatler photoshoot to mark her coming of age.

It is her first official portrait and one that is likely to launch her as the most glamorous young royal around today.

For despite being the great-great-great-great-granddaughter of Queen Victoria and sixth-in-line-to-the-throne, Eugenie has happily remained under the royal radar - until now.

"Eugenie knows full well what is expected of her as a member of the Royal Family and is happy to take part in all those balcony appearances with her grand-mother but she is the last person you will ever find using her title outside of royal circles," says a family friend.

Unlike her cousins, William and Harry, the nearest Eugenie has come to a public scandal was being turned away from the VIP section at a music festival two years ago because the bouncer didn't believe she was a princess.

That's not to say she doesn't have her moments and with a possy of dubious friends including Peaches and Pixie Geldof, it's no surprise that her own father admits she had been a "tearaway" at times.

From plain princess to glamorous cover girl, Eugenie substitutes the High Street wardrobe she favours for designer clothes

As well as the obvious physical differences from her elder sister, Beatrice, Eugenie is also the more worldly of the two and has a host of admirers at £26,000-a-year Marlborough College, where she is a straight-A student studying for A levels in Art, History of Art and English this summer.

She does, however, tell Tatler magazine that she and Beatrice - dubbed The Yorkies by friends - are still very close.

"Like all sisters we have silly arguments about unimportant stuff, but we do love each other to death," she says.

She describes her parents as "the best divorced couple I know," adding: "They just always went out of their way to make us feel loved and secure."

And she raves about her grandmother the Queen - whom she has nicknamed "Supergran" - saying: "Truly one of the most amazing women ever. She is also very funny....All I can say is that she has this air of magic about her.

Happy family: Proud mother Sarah Ferguson with Eugenie, right, and sister Beatrice, left

"And she is incredibly wise. What doesn't she know?!"

Despite her blue blood, Eugenie's life hasn't always been easy. At the age of 12, she underwent a seven-hour operation to correct a curvature of her spine, during which surgeons had to insert two titanium rods into her back which are still there today.

Happily the operation was a complete success and despite predictions that she would be a "hunchback" by the time she was 18, is clear that Eugenie, who grew two inches taller as a result of the operation (she's now an enviable 5'7'') has suffered no ill-effects.

Like most girls of her age, the arty princess - who has a Norfolk Terrier called Jack (named after the 24 television character) and devours books, most recently The Kite Runner - is addicted to using her computer and even has her own pages on social networking sites such as MySpace and Facebook.

She loves to drive her parents mad, she says, by having her i-pod on loud, says her favourite foods are hot dogs and loves television shows such as Desperate Housewives and Lost.

She also jokes about her name saying: "Whenever we used to meet foreign people who were struggling with it, my mum and I would help them by saying, 'It's like Use Your Knees!'

"But whatever. I am now used to every pronunciation."

Despite her mother's predilection for dressing her daughters identically, Eugenie is also steadily developing her own sense of style.

On the cover of Tatler she is wearing a purple silk-duchesse satin gown by Ralph Lauren with gold, diamond and emerald earrings by Bulgari.

Inside she has chosen a silk and metal dress by Daks Luxury by Giles Deacon and a white-gold and diamond necklace by Chanel Fine Jewellery.

Normally, however, she favours the High Street with thigh-skimming dresses from Topshop and Reiss often topped off with a jaunty little beret.

Unlike Beatrice, who marked her coming of age with an over-the-top costumed ball, Eugenie is planning a small celebration with her family at Windsor Castle over the Easter weekend (her actual birthday is on March 23) followed by a night out clubbing with her mates.

It's likely to be the last time this anonymous young royal will be able to enjoy a night out away from the public glare.

The April issue of Tatler is on sale from Thursday.