Thandie Newton: raging beauty

Thandie Newton is not the sort of actress you need to coax, flatter or cajole for revelations of any sort. 'Honestly, I could tell a story,' she says, seconds after sitting down, 'that would make your hair stand on end. Literally. Honestly, it beggars belief. But I'd better not because people will have a reaction to it.'

Moments later she is telling me everything – the director, 'the typical Hollywood grosser', who screen-tested her when she was just starting out, and how, in the interests of the role, he told her to lie back, one leg over the chair, and touch herself, and then years later she finds out he would show the tape, 'literally shooting up my skirt', to people at night. 'I did it because it was sort of a sexy role. I was totally naive,' she says, wincing.

And then there was the photographer who dressed her, 'the most unprovocative 18-year-old in the world', in a leather miniskirt and high patent heels and made her lean over a school desk, 'a f – school desk' .

She met that same photographer a few weeks ago. 'I had this real eruption of emotion. I didn't because his kids were there, but I wanted to say, "Shame on you."' Her eyes burn, her lower teeth jut forward in outrage. 'It's a minority of people who want to exploit you in the creative world, but if you want to be opportunistic in that way, it's brilliant.'

Thandie Newton, who is 38, has been in the spotlight since auditioning on a whim for John Duigan's Flirting at the age of 16 (fitting it in before her degree in social anthropology at Cambridge), and lives what many might imagine to be a gilded life.

She is unusual for treading a careful path between films that bring in the big bucks (Mission: Impossible II, 2012, Norbit) and work, such as The Pursuit of Happyness or Crash, for which she won a Bafta, or her latest thriller Retreat, set in a Scottish island, that feeds her intellectually.

She is pin-slim and beautiful – her face has an almost luminous quality – and she has attained domestic happiness with the director Ol Parker, the pair cleverly managing their work/life balance to make sure one of them is always on hand for their two young daughters.

For all this, we are far from the realm of airy-fairy or glitzy or smug. Newton will tell you about Nicole Kidman, sure ('always lovely'), or the 'modesty cup' worn by Tom Cruise in the sex scenes in Mission: Impossible II ('last time I mentioned this his "people" rang up to complain'), but she would much rather talk about the importance of emotional intelligence in relationships, or the sexual violation of women in the Congo.

She is fond of 'hello?', and her sentences generally turn up at the end, but, like the passing swipe she gives to my knee, these are weapons of rhetoric. She is a woman impassioned, aware of the importance of tackling the issues of identity and pain head on. 'I feel like my role in life,' she says, 'is to empower women to live in the moment as much as possible.'

We have met in a bar-restaurant attached to the studio where she has been photographed, near to her home in north-west London. It has been a good session: 'The loveliest photographers are the ones who sense what you are like and who you are and they bring you out.'

She is wearing chunky high-heeled boots, moleskin trousers and a swath of caramel soft cardigan, her hair pulled back to reveal the perfect angles of her face: the full cheekbones, the widely spaced eyes, the curved lips. One of the difficulties in her life is being turned down for roles for being too good-looking.

'That was what was so liberating about Oliver Stone casting me to play Condoleezza Rice [in W]. I was, like, "Why the f – has he chosen me?" while loving the fact that he's chosen me. I'm an actress. Let me change.'

She says at one point that she 'feels watched all the time. When I am out and about I do feel watched. It's become second nature. The only time I get to be private is in my work. That is when I liberate the ego.' She closes her eyes briefly. 'The blissed-out sensation of liberating the ego.'

Earlier this year she gave a talk for TED, which describes itself as a 'non-profit organisation devoted to Ideas Worth Spreading' (other speakers include Steve Jobs, Niall Ferguson and Elizabeth Gilbert), on the theme of 'embracing otherness'.

Here she discussed her own feelings of anxiety and shame and the experiences that taught her to stop valuing self-worth above all other worth. 'You know, at first I was like, "Yes," thinking, "No, what am I going to talk about?" but Pat Mitchell, the organiser – you know who she is: she was like Oprah before Oprah – said, "You have a unique perspective." And of course I have. Also I am politically astute, active as I can be, a bit of an academic when it comes to psychology. It was so up my alley. I built the shops on that alley.'

Newton's perspective arises from her upbringing. She was born in London to an English father, a lab technician, and a Zimbabwean mother, a nurse, and except for three years in Zambia spent most of her childhood in Cornwall, living above an antiques shop with her parents and younger brother, Jamie (now a television producer).

Penzance in the 1970s was not the best place to feel different and she struggled with insecurity. A talent for dance and a scholarship to the Arts Educational School in Tring in Hertfordshire provided something of an escape, but she became bulimic – 'of course I did' – and success as an actor had its own pitfalls: a six-year affair with Duigan, the director of the coming-of-age film Flirting and 23 years her senior, which led her to seek therapy.

She expounds on those who 'prey on other people's innocence and naivety', on the trusting nature of her parents – 'why would you look over your shoulder at things like that?' – but clams up when I mention Duigan. 'I don't want to talk about him,' she says with uncharacteristic restraint. 'It's cooler if it doesn't boil back down to that.'

Acting provided an outlet for her demons, but also complicated them. 'I thought, "What the f – is wrong with me? Am I so shallow, so lacking in substance, that I feel more myself when pretending to be somebody else?" My poor ego had been created out of racial insecurity and shame. You know' – she shrugs – 'most people's lives are a struggle. This is just my recipe. You have a choice with your experiences, even if they have been negative and difficult, and one thing you can do is turn pain to power.'

Two things have helped Newton undergo this transformation. The first is therapy, which she first discovered in her twenties. Her openness, and thoughtfulness, are those of someone who has spent a long time on the analyst's couch. Asked whether her daughters, Ripley, 11, and Nico, seven, get on, she replies carefully, 'I love how the challenging nature of their relationship sets them up for many relationships in life.' She describes meeting her brother Jamie 'spiritually for the first time' when they were young adults. And on Parker she doesn't so much gush as dissect: 'An incredibly bright man but with deep compassion. The most unthreatening human being, but still incredibly … still challenging in a very healthy way.'

Yoga and the guidelines to life provided by Buddha have been a great support along her path: 'I must find out if it is a philosophy or a religion.' A couple of years ago she made a foray into the Hoffman Process, an eight-day residential course to beat anxiety and depression. Was that useful? 'Hello?' she says. 'It's like being able to start again. You shift baggage you don't even know you've got. It's really smart. I arrived at the Hoffman thinking I am the most uninhibited person on this planet. Wow.' She shakes her head. 'I am incredibly private. And I needed to shift some rage.'

It is shifting the rage, moving from the private to the public, that has also helped in the quelling of Newton's ego. Aware that 'celebrity has its own authority in the world', Newton has sought out roles that might just change the way people think. She took on the role of a Congolese aid worker in ER largely because 'I was so struck by how this TV show wanted to create a platform for Africa'. And she is thrilled to have been given her first theatrical part as Paulina Salas in Jeremy Herrin's new production of Ariel Dorfman's Death and the Maiden. 'It is the role for modern women: politics, torture, rape – it is so up my alley.'

Newton is also on the board of V-Day, a movement set up by Eve Ensler, 'a wonderful and empowering force of nature', who wrote The Vagina Monologues, to employ art to end violence against women. In February they were in the Congo and Newton says she doesn't care if this isn't really what we have come to talk about, 'I'm going to talk about it anyway. It is one of the most important things I have been involved with. Women have become the gross collateral of all those wars. The rape of women in Bosnia, Afghanistan, pales into insignificance when you see what is going on there. Sexual violation is a weapon of all these wars. It is cheap and it is effective.'

She goes on to talk about the 'hot coal of rage' felt by the children who witness the atrocities, and for a moment you see it in her eyes, too.

But it is mid-afternoon and Newton has children of her own to collect from school. (You suspect she would talk all day if you didn't remind her.) She gets up from her chair. 'I don't feel like a victim now,' she says before she goes.

There is a car waiting for her, but normally she takes the bus. 'On public transport people don't expect to see me so it's fine,' she says. 'And if they do come up, like this lovely guy in Pret A Manger yesterday, and say, "Oh, I really love that movie you did," you are two equals having a conversation. But when it's "You're that one off …" or "Are you famous?" I feel like I have become one of those free newspapers you get on the Tube.'

She slings her bag over her shoulder. 'I hate that. I become less than nothing.'

'Retreat' is in cinemas now and on DVD/Blu-ray from tomorrow. Death and the Maiden is at the Harold Pinter Theatre, London SW1 (0844 871 7622; deathandthemaidentheplay.com)