Style icon Sarah Jessica Parker talks to Susan Griffin about juggling a career and motherhood, Sex And The City 3 and her new film I Don't Know How She Does It

Sarah Jessica Parker is looking anxious. You wouldn't expect it considering we're talking about her toddling twin daughters having the ultimate wardrobe to raid.

Leaning in, the petite actress says: "The thing is, I'm afraid that one of them will be quite tall. I know it sounds crazy, but my father's six foot and I don't know what's going to happen. There's going to be this terrible imbalance."

At the suggestion the longer legged twin could inherit the handbag collection instead, a wide smile spreads across her face and clasps her hands together with what looks like unmitigated relief.

"Oh yes, the handbags!"

It's very Carrie Bradshaw, the Sex And The City character for which SJP's synonymous.

For six years, 12 if you include the two movies, fans have followed Carrie's happiness and heartache. We cooed over the clothes and celebrated with a cocktail when she finally wed her true love (Big, as if you didn't know) while her relationship column became an ode to single girls the world over.

It's little surprise that so many women think they know Sarah Jessica Parker.

"Carrie's always with me, it's just the way it's going to be after 12 years," she says, her small frame dwarfed by the dimensions of the sofa she's perched on.

She's wearing a delicate lilac dress, matching pointed heels and a bright yellow jacket that shouldn't work, but somehow does.

Her long hair is loose and wavy, her make-up's natural and her piercing blue eyes have the faintest hint of lines around their edges.

It's the sort of beauty that's approachable and attainable, which is a huge part of SJP's appeal.

Tellingly, for someone of her status, there's no entourage. She talks openly about her home life in New York with Matthew Broderick, 49, her husband of 14 years, and children, James Wilkie, 8, and twins Tabitha and Loretta, who were born via a surrogate two years ago.

Her latest role is a move away from her fabulous single girl about town persona. I Don't Know How She Does It sees SJP playing Kate Reddy, a wife, mother, career woman and juggler par excellence.

Based on a novel by Welsh journalist Allison Pearson, it pulls back the curtain on the juggling act known as 'having it all'.

"What's impressive is the book was published 10 years ago and it's more relevant today, in this economic climate, than it was then. I don't know if that's prescient or just unbelievable," she says in a girly voice that belies her 46 years.

"There are things in it that are familiar to me, and I also knew it was a story that'd resonate with women all over the world."

A famous actress and multi-millionaire, you wonder whether SJP can truly relate to the average working woman. But first and foremost, she's a wife and mother.

"I have enormous concerns about my children's health, education, wellbeing; the kind of foods they eat, culture they're exposed to and their faith in themselves.

"These are the things mothers all over the globe worry about and ponder late at night."

In recent years, there has been something of a post-feminist backlash to the notion of being able to "have it all" but SJP believes you should strive as if you can.

"It's a more satisfying destination than resigning yourself to some place in the middle; a mediocre halfway point," she says.

"But I'm also realistic of what can and can't be achieved in a day, let alone a year. I have some maturity now, that I didn't used to have."

She was only eight when her showbiz career began with a TV movie, and 19 when she made a memorable appearance in 1984's Footloose opposite Kevin Bacon. But there are no regrets about starting out so young.

"No, I'm glad I did," she says. "I had great experiences. I worked in a different time when the emphasis was entirely different. Being a great actor and merit was everything. It wasn't about being rich or famous, it was simply about hard work. I wouldn't trade those experiences for anything."

According to reports, James Wilkie has aspirations of following in his parents' footsteps.

SJP has "mixed" feelings about this: "I hope he pursues it with seriousness if it's what he wants to do. The only rule is he has to go and finish a four-year college course - then he can do whatever he wants."

Today, she remains stoical about being one of the world's most famous faces.

The school run, for example, finds her trailed by paparazzi eager to sell images of the style queen looking less than picture perfect.

"There's not a lot you can do. You're a mother, so you dress appropriately for the weather and in a way that doesn't embarrass drop-off, and that's it.

"If you have a zit, you try and cover it. You put on a big hat and some sunglasses, and hope that camouflages the little bit of a wreck you are."

But with the lows come the highs, says SJP, as she recalls a recent trip to Moscow. As a former ballet student, she was desperate to see the Bolshoi Theatre.

"I've heard about it my entire life. It's the birth place of so much of what I admire about the world of ballet."

Only she discovered it was closed for renovation work.

"I was just hanging around and then I heard some of workers say, 'Sarah Jessica Parker' and was able to get inside," she says.

"I recognise that I probably wouldn't have been able to do that if I had been a civilian, so there are wonderful things that have happened to me because I've been part of something that's been meaningful to people."

And that brings us nicely back to the subject of Sex And The City and whether it's true a third film's in the pipeline.

The second movie may have been mauled by the critics but it was still a box office smash and the fans will always crave more Carrie and co.

"Very casually a couple of years ago, Michael [Patrick King, the executive producer] mentioned an idea which I thought was very good. It's definitely something I would want to do if we ever revisited," she says, those eyes twinkling again.

"It would be great. But that would be the last..."

Extra time - Sarah Jessica Parker

:: Sarah Jessica Parker was was born on March 25, 1965, in Ohio.

:: She's one of eight children if you include step-siblings.

:: Former boyfriends include Robert Downey Jr and John F Kennedy Jr.

:: One of her best friends is Willie Garson, who played Carrie's BFF Stanford in Sex And The City.

:: World famous shoe designer Manolo Blahnik has named a shoe in her honour.

To find local screenings for I Don't Know How She Does It, click here.