Kristin Scott Thomas has arranged to meet me at a restaurant in the East End of London, which seemed peculiar. What was such a well-shod woman doing in such a down-at-heel postcode? Typically, interviewers who are granted an audience with England’s thorniest rose travel to her home city of Paris. They meet her in an upmarket cafe and watch as she eats a steak (bloody), drinks a coffee (black) and then become increasingly agitated as their questions freeze and shatter under the frosty glare from her hooded eyes.

They scuttle back to their desks in London, where women journalists write sniffily of her froideur, while the men mostly perve about her beauty.

And lo, though Scott Thomas is an actress of 25 years’ standing, who starred in the most beloved British film of the 1990s – Four Weddings and a Funeral – and the most celebrated – The English Patient – she remains, as the late director Anthony Minghella once said, “unknowable”. Hugh Grant, her Four Weddings co-star, put it more brashly, saying she needed “warming up” every day on set. It’s a fair comment. Scott Thomas never gives an inch more than she wants to, not even on screen. Anthony Lane, the film critic, marvelled that she was like Audrey Hepburn, with an “infuriating habit of stealing a scene, or an entire movie, without appearing to make a grab for the goods”.

It’s no coincidence that all the best quotes about Scott Thomas fall from the mouths of men. At 48 she could still make a good dog break his leash, though – on screen, at least – I always thought her angular beauty had a niche appeal. Her powers of seduction are nevertheless fierce, and she has a particular gift for making overgrown public-school boys gaga. When Jeremy Clarkson interviewed her on Top Gear last year, she deftly disarmed him with a thrilling barrage of haughty chin-raising, eyebrow-arching and quips, leaving a gooey-eyed Clarkson purring that, yes, maybe his Lamborghini was terribly uncool and he would flog it immediately just to please her.

Yet, the occasional flirt aside, Scott Thomas remains a mystery. Is she some automaton, sent to seduce the world with her chilly wit and jutting cheekbones? At first glance, I could well believe it. Here in east London, she is on a break from rehearsing The Seagull by Chekhov, which she performed to great acclaim in London last year and is now appearing in on Broadway. I sent her agent a list of “movie-star-friendly” lunch spots near her rehearsal rooms – no easy feat in this scruffier end of town – and she opted for a tapas joint. Save for a few waiters, the room is empty when I enter, not that it would have been hard to spot Scott Thomas sitting against the far wall, wrapped in the thinnest white cashmere, hair blonder than it used to be, and her skin that peculiar shade of Hollywood butterscotch. The effect of her beauty – which is more extreme off screen – in this humdrum setting is bizarre. It’s as if Renée Adorée has stepped onto Albert Square.

It’s no wonder she’s looking so good. After some low-impact years for her professionally, this autumn Scott Thomas is back. Not only is she on Broadway, but she has three films slated for release: a British period piece (Noël Coward’s Easy Virtue), an American crowd-pleaser (the chick flick Confessions of a Shopaholic), and a harrowing French drama. The last, I’ve Loved You So Long, in which she plays a woman trying to readjust to civilian life after 15 years in prison, performing entirely in French, is generating an Oscar buzz. It would be her first nomination since The English Patient 12 years ago. Her personal life – which she likes to keep very personal – is also back on track. In 2005 she separated from François Olivennes, the renowned French gynaecologist and her husband of 17 years. There was talk that she was having an affair with an actor almost 14 years her junior, but – French privacy law being what it is – she was only busted when she spent a few months doing a play in London. Her lover – or “Toy Boy Lover!”, as he was known in the tabs – was Tobias Menzies, her co-star in a 2003 production of Three Sisters. They saw one another on and off for a year, but she has since split from him and hence is on good terms with her ex-husband. She has moved into an apartment on the Left Bank, selects her jobs to fit around her children’s school terms, and is happy about getting older, as it lets her indulge in one of her favourite pastimes: being rude to young people.

I watch her for a couple of seconds before going over. She is putting her hair up, then down again, every inch l’actrice. But when she sees me approach, she visibly gathers herself together and throws on a smile that doesn’t quite reach her eyes. Her hand is cool to the touch and, for all the wow factor, it occurs to me that interviewing Scott Thomas could turn out to be as rewarding as defrosting a freezer. She uses all that physical allure and verbal reserve as a nifty shield, but who knows what’s underneath? Maybe nothing.

With the food ordered (she opts for lamb – served bloody, of course), I decide to come out with it. Will I have to warm you up, like Hugh Grant, I ask. She smiles coolly. “Oh no, I’m pretty quick off the mark now,” she says, adding she believes the perception of her as uptight is unfair. “I did have a face that often looked very distant, supercilious, but it was just my face,” she complains, her face, at this point, haughtier than ever. “But I was hiding because I was shy and desperate that no one should notice me. It’s so nice to be more confident now. It came with maturity, and it’s a huge relief.” Which rather suggests she has become easy-going in middle age. Wrong. Instead, she says dispensing with some of her nerves has allowed her to release her inner dragon. “I’ve become what they call in French exigeante – a polite way of saying a pain-in-the-arse stickler. I want everything to be the best, to be done properly. If I’ve asked someone to do something and they don’t, I get terribly cross.” Are you difficult with directors? “Yah, I am. I’m not that assured in the rest of the world, but with my work I feel I know what I’m doing. Sometimes I make a complete arse of myself, saying we can’t do it a certain way, and I can see everyone thinking, ‘Just shut up – get back in your box.’ There’s a hush when the technicians look at their shoes when you know you’ve gone too far.”

Have you alienated people? “Oh, I’m sure I have. But,” she shrugs, “if you find them irritating or dim, it’s difficult. I can get very angry with the director, and they can get very angry with me, and there can be a huge showdown. The director is the one who gives you your boundaries, so I test them like mad.” She pauses. “But I’d hate to think I was malicious. Other times I’m delightful,” she adds, coyly.

But you can be withering when cornered? “Oh, God, yes. There was the most awful young runner on the last film I did, and I was as withering as possible with him. The first thing he did was me tutoyer [address her with the familiar tu rather than the polite vous], which was – of course – absolutely not on. I was so evidently not his little mate from school. Ooh, I was frosty – not acknowledging him, walking away when he approached me…” She chuckles. “The silly boy was poison, utter poison.” Phew.

“Young people are very frightened of me, too, which I enjoy,” she continues, “especially young girls. But I had a PA for about eight years,” she adds quickly, by way of defence. How did she last eight years? “She could read my mind, that’s how.” Are you a woman’s woman? “Yah,” she trills, unconvincingly, “but I couldn’t think of anything worse than a girls’ night out. I’d rather drink ink.”

This little rant has livened her up no end. She launches into a rebuke of her agents, who, through minor confusion, caused her to put back our interview by 15 minutes. “I like being on time,” she says so sternly that I ask if her fondness for it is on the level of OCD. “I don’t think I can answer that,” she says, suddenly more nervous. “I don’t think so.”

But the nerves she claims to have left behind, and her new need to wither those around her, must both be underpinned by something. She drops the Grand Bitch act and addresses me seriously. “I can’t bear being disappointed, to expect something and for it not to happen the way you want. For example, I’m terrified it [The Seagull] is going to be a massive flop in New York.” I raise an eyebrow. “But it might!” she cries. “I spend an awful lot of my time expecting the worst.” Why? “If you want to get psychoanalytical about it, you could say the biggest disappointment in my life was when my dad died,” she says, quietly. “When you grow up with that massive event, you daren’t expect things – so it’s very bizarre that I chose this path. The world I work in, that I live in, that I breathe, is one of constant let-down.”

Scott Thomas was born into a naval family stationed in Redruth, Cornwall, in 1960. Her father, Lieutenant Commander Simon Scott Thomas, was a pilot with the Royal Navy and a devout Catholic. Her mother, Deborah, had trained as an actress, “but then she met my dad and went into full-swing wifedom, and that was that.” Scott Thomas has a handful of happy memories of early childhood – playing dress-up and putting on plays – but before she was five her father died in a plane crash. As the eldest, she was encouraged not to cry, so as not to upset the younger children. Later her mother married another pilot, who, in an unimaginably cruel twist of fate, also died in a plane crash, six years after the first one.

Deborah, then in her early thirties, was left twice widowed with five children. Later, during a brief stint on a drama-teaching course in London, Scott Thomas recalls, “I got needled a lot for being middle-class. They thought they were so right-on and took the piss out of me. I thought, ‘You don’t know anything about me.’ Just because I’d been to a convent school, and spoke a certain way, did not mean I was loaded. It was a struggle growing up. You can’t bring up five kids on a naval pension and have it be easy and comfortable. My mother had to fight tooth and nail to give us the education she gave us, ringing on doorbells, telling people, ‘I went to this school – my children need to go there.’ I’m fantastically in awe of her courage. It made me so angry when people assumed I had this easy life.”

As a boarder at Cheltenham Ladies’ College, she didn’t thrive. “It was a tough time. I was aware I was lucky to be there, and at the same time I’d just lost my stepfather and I was always being put down all the time, always in the C-stream, rubbish at everything. It gets to you after a while, being the thick one.” She was stunned when she got onto the drama teachers’ course at the Central School of Speech and Drama. “It was the best acting job I ever did, saying I wanted to be a teacher, that I really believed drama could help young people, that I wanted to get out there to some underprivileged areas – Hahaha!” Once she was there, a tutor thought she might be good enough for the actors’ course and sent her off to audition. “They got me in their office, these two women, and said, ‘There is no way you could be an actress. If you want to play Lady Macbeth, then join your local amateur dramatic society.’ I was 18 years old – so cruel!”

By this point she was fed up with the course and fed up with England. Since her mid-teens she had been visiting Paris as part of an exchange programme for naval girls, so she upped sticks for the City of Light to become an au pair. She never came back. “People always say I’m snooty about England, but I love coming to work here,” she says, before rather undoing her point by adding: “though I’m so glad I live in France, and I’m not the only one. Look at all the English OAPs buying up half the Dordogne. They all know they’ve got to get out of England as well. It’s une qualité de vie.” She is swoonsomely in love with her adopted home, citing everything from the “perfect bread” (which saw her weight reach an improbable 12 stone in her twenties) to the lack of “palaver” she is afforded by the kinder attitude of the French press, which means she can walk the streets unbothered by photographers. That must have been handy during the breakdown of your marriage. “Oh, God, yes. There’s still rumours and backbiting and bitchery that goes on, but not on the scale of Britain.”

In her early twenties she got into a Parisian drama school, where she met her future ex-husband, an owlish medic who had enrolled in acting classes to meet pretty girls. Their marriage was apparently a “fairy tale” – she the film star, he France’s leading in-vitro expert. Not that there weren’t problems. At one point I praise her organisational skills. “I wish you’d tell my ex-husband that,” she sniffs.

She has also suffered from depression and, raised as a Catholic, believes she has an overdeveloped sense of guilt.

“I have Catholic guilt, then I learnt Jewish guilt from my husband’s family. They think you want to join the gang – it’s so frustrating, though I did think of converting for a time. Someone very dear to me said I shouldn’t bring up my children as Catholic, I should bring them up as Jewish, as it’s a much better religion.” What did you say? “I ran away at that point,” she laughs.

After graduating from drama school, her first job was a Marguerite Duras play, performed in a field in Burgundy.

“I got my first newspaper review.” Was it a good one? “Oh yes,” she says smugly. A year later she was cast as the female lead in Under the Cherry Moon, a vanity project for the singer Prince. It was a total flop but she was on the map, and her subsequent career has run the gamut from Euro-dross, such as Roman Polanski’s Bitter Moon, to megabucks Hollywood and quality independent films (Gosford Park). She had always intended to be a theatre actress, though, and by the late 1990s she was bored with playing “older gents’ crumpet” to the likes of Harrison Ford (Random Hearts) and Robert Redford (The Horse Whisperer), so she decided to stay nearer to home, have another baby – she has three children, Hannah, Joseph and Georges, who are 20, 17 and 8 this year, respectively – and concentrate her efforts on French film and British theatre, only taking the occasional American gig when her US agents beg her to.

It was a smart move that is beginning to pay off, not least for all this Oscar talk. “I don’t see any point in even thinking about that, because I can’t see them giving it two years running to a French performance,” she says, pointing out that Marion Cotillard won it for La Vie en Rose last year.

Her career is exactly where she wants it, though. She is coping with the “disappointment”, she laughs. “I used to like getting the offer so then I could say no,” she laughs. “Now I’m not so bothered.” And now she’s a bit older, the parts are picking up, as she likes playing grown-up women. She still suffers from “dreadful typecasting” outside France – where “they let me play anything, not just posh bitches” – and feels zero nostalgia for the way she used to look. “When I moved house I was looking through some old photos, and I don’t know what people were talking about with this idea that I was so beautiful. I thought I looked horrible. I honestly think I look better now.” Actually, she’s right. Up close, age has softened some of those angles. “Once you’ve calmed down about whether you’re seductive and attractive – the idea of wanting to please, wanting to be loved – you can do all the things you never could before. Walking into a room used to be hideous for me; now I don’t mind at all.”

It’s true that her face isn’t the only part of her to have softened. She has begun to open up. For a woman who usually keeps her own counsel, I’m taken aback when, discussing the deaths of three of her past directors – Robert Altman, Sydney Pollack and Minghella – she actually begins to cry a little. “Awful, such a loss,” she says, shakily. “As Richard Curtis said at Anthony’s memorial, ‘There are many more people in this room I would wish to be dead before him.’ She is also comfortable enough to talk about her insecurities. “I don’t think I’m the brightest spark in the box,” she sighs, “and that pains me.” You’ve been hanging out with too many Parisian academics. “Yes.” Who wants to be like that anyway? “I do,” she says softly.

Behind the snooty-cow act, she is still nagged by doubt and insecurity. She says her stage fright will become “horrific” in the lead up to her Broadway debut. It’s ironic – because, in the same way that a few more miles on her clock has thawed her personality a little, made her more likable, it has also done wonders for her day job. Judging by her turns in The Seagull and I’ve Loved You So Long, she has gone from being a really good actress to a great one. But thanks to that childhood of hers, she can never fully shake off the doubt. “I’m a terrible worrier. I’m the sort of person who has a Rolodex of worries. I lie in bed at night thinking, ‘No, don’t worry about that one yet – choose another one!’”

Do you worry that you kept the world at arm’s length for too long? “Perhaps. I was in Italy last week, and some Italian wit said to me, ‘You have to be careful with mysterious women, because sometimes when you get behind the mystery, all you find is stupidity.’” Is that why you have kept your guard up for all these years? She opens her mouth as if she is about to say something, then turns it into a cryptic little smile instead. “Anyway, I can’t be late for rehearsal,” she blurts out of nowhere, leaping to her feet.

She scrapes her hair back into a bun and pulls on her Burberry mac, belting it tightly around her tiny waist. She bestows two cursory air kisses, and a barked instruction not to look at her toenails because her pedicure isn’t up to scratch, and hurries halfway across the restaurant at a speed that borders on the offensive. But then – as if she has suddenly thought better of it – she turns and gives me a goofy little wave goodbye. It doesn’t sound like much, but for Kristin Scott Thomas, this is progress. A small sign that, nearing 50, she is finally happy to let herself go a bit.

I’ve Loved You So Long is released in the UK on September 26. Easy Virtue is out on November 7

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