Just what is it about this posh heroine that warrants a return to the screen, asks Shane Watson

At a photographic studio somewhere in east London, the new Lady Penelope is throwing her toys around. In the make-up chair, staring crossly at herself in the mirror, is Sophia Myles, the 24-year-old actress who plays Lady P in the forthcoming movie of Thunderbirds, the cult 1960s television series. Myles is showing a steely determination to be styled in the manner she sees fit, regardless of the wishes of those around her. In fact, as she sits at the mirror, swivelling her head from side to side before dismissing another attempt at compromise on the hair and make-up, for a moment it seems she might be inhabited by the spirit of Lady Penelope herself. Girls don’t tend to be big on hauteur these days. They don’t usually have buckets of queenly attitude. When I draw her attention to something on the rail that looks a little risqué for Lady P, Myles pronounces it “trash”, with a slow arch of an elegant brow.

Millions of viewers who are now in their forties know Lady Penelope as the calm oasis in a storm of International Rescuers: the elegant, glacially posh counterpart to those goofy, permanently smiling Tracy boys. If you were the female fan of the original series, Lady P was the reason you switched on. She was pretty, unflappable and unapologetically grand. Though not spoilt, she knew what she liked (an evening Pernod, cocoa before bed) and employed a loyal chauffeur called Parker, who saw to it that she always got what she wanted and was never disappointed. In short, Lady P was the woman every girl hoped to grow up to be. She provided It-girl glamour, but had brains and a job. When I e-mail a highbrow friend to ask her why it is that every girl wants to be Lady P, she replies in seconds: “She doesn’t need Botox. She doesn’t get parking tickets. She doesn’t have to go to management conferences. She commands total respect. And nobody calls her Penny.”

“Different territories respond in different ways to Lady P,” says Myles. “In Japan, it’s all about her pink clothes. Americans like the grandness of her. In England, they want to know if Lady P and Parker are having sex.” Myles’s resemblance to Lady Penelope may be evident in her looks, but in reality, the original Lady P was more of a cross between Diana, Princess of Wales, and M in character. Myles is noticeably younger than the original Lady P, who always seemed to be more of a worldly thirtysomething. Her hair is blonde (albeit not as big and backcombed as Lady P’s) and her eyes are startlingly blue (though without the slow blink). What she does have is the grown-up, well-spoken voice of a girl who probably has her own pony. “I mean, it’s not like I’m the spitting image of the puppet, but I think they saw potential,” she says, coolly, taking a sip of her mid-afternoon glass of chardonnay.

The voice is an accident of her west London upbringing. “I was education in the state system, so I’m nothing like this boarding-school girl,” she protests. But you don’t need to live at Cliveden and have a title in order to channel lady with attitude – lady who lolls in a bubble bath giving instructions to her chauffeur while sipping champagne. “Tea,” Myles corrects me, that eyebrow lifting a fraction. “Lady P likes champagne in the back of Fab 1, but in the bath it’s tea.”

The hope is that Myles’s Lady P will inspire as much admiration in a new generation as did her puppet alter ego. In the film, her character has acquired plenty of Avengers feistiness. “I think she’s been given an injection of girl power,” says Myles. As for Lady P’s USP in the overcrowded world of modern superheroines, it’s her breeding. “She’s intelligent, confident and sexy without being provocative,” Myles says. “I think to have a role model for young girls who isn’t tits-hanging-out and midriff-on-show is quite nice.”

In other words, Lady P can play the posh card like nobody else. She genuinely is to the stately home born, and is not in the least bit apologetic about it – a position that hasn’t always worked for a girl in the decades since Thunderbirds was conceived, but now seems to be back in favour. Having been pushed underground for a while, rampant poshness (including a cut-glass accent) is now back in fashion. This is partly thanks to the likes of Tara Palmer-Tomlinson, who you may not automatically associate with classy glamour, but who has proved herself to be a jolly good sport (the new generation of Lady Ps can’t afford to be snobs). Partly, it’s a reaction to the rise of the trashy society girl, spearheaded by Paris Hilton. Ten years ago, a character such as Lady P, who is happily single and rather self-contained, would have been far too starchy and buttoned-up for contemporary tastes. Now, post-Britney and Paris and Big Brother and gangsta rap and binge-drinking and girls focusing almost exclusively on their sexual appeal, Lady P seems refreshingly dignified and feminine. She may not be Beyonce, but she represents values that young women should aspire to, such as self-respect and independence. When I suggest that her character would surely be in the category of women who expect men to pay for dinner, Myles is affronted. “Lady P doesn’t need a man to give her anything,” she says, her brow knotting prettily. “I think she’s very much an independent girl who doesn’t want for anything because she’s bought it all herself.” Pressed for more details of the modern Lady P’s tastes, Myles thinks that she probably “eats very well and doesn’t do faddy diets. She’s not remotely snobbish. On the other hand, she isn’t in the habit of revealing much about her private life, which makes her all the more fascinating”.

Later, as I leave, Myles remembers to tell me that, of course, she needed elocution and movement coaching before she was ready to play Lady Penelope, but if you ask me, that was purely detail. There aren’t a lot of 24-year-olds whom you could call “Your ladyship”, but Myles is definitely one of them.