"I lived a very normal, middle-class life in Mumbai. I travelled on local trains and buses, but suddenly that world was shut down for me out of need for safety and security," she says. "The constant being looked at, being trailed by the paparazzi — the invasion of privacy felt very disconcerting."
Falling in love with her British co-star, Dev Patel, only intensified the attention. The picture-perfect couple stayed together for six years — and remain friends — but have said that part of what sparked their relationship was that "we were both in this surreal situation".
A decade on, Pinto thinks she has found a "new normal". She has a new boyfriend, American adventure photographer Cory Tran, who describes himself as a traveller and adrenalin junkie. Indian newspapers have been speculating that they may marry after a recent trip to that shrine to love: the Taj Mahal.
"So much time has passed since Slumdog now, I think I've learned the art of blending in," she says. "There will always be that one person who calls out my name and wants a picture when I am walking across Leicester Square, but I go out without make-up unless I am promoting a film. I'm on guard, but I'm a lot more relaxed."
In her 30s, Pinto has grown into a fearless, outspoken feminist who has put her money where her mouth is in supporting women in her industry. She is part of not-for-profit group, We Do It Together, which provides finance for features and documentaries focusing on women's empowerment. She campaigns for women's education and supported Tanushree Dutta, the first Bollywood actress to complain of sexual harassment.
Pinto does, though, acknowledge that her face has largely been her fortune and, in 2009, signed a seven-year contract with L'Oreal to promote the company's products. She has drawn the line at promoting skin-lightening solutions, which are popular in India.
Yet, earlier this week, Pinto said that she believed L'Oreal had colour-corrected her complexion in early advertising shoots without her consent — "I'm sure they did because that's not the colour of my skin you saw in a few of the campaigns" — something the cosmetics giant has strongly denied.
She is in London for a few days for the opening of Love Sonia, a brutally compelling tale of sisterly love. Pinto, who now lives in Los Angeles, first read the script while she was filming Slumdog Millionaire.
"It's taken 10 years to get it to the screen because it wasn't the easiest film to finance. In India it was thought to be too dark," she says. "Hello? The world is dark."
The story revolves around Preeti and Sonia, teenage girls from a remote village, who get caught up in India's burgeoning sex trade. After the repeated failure of his crops, their desperate father sells Preeti to a local landlord, who ships her off to Mumbai.
Sonia follows, hoping to rescue her sister, but is herself kidnapped and forced into a backstreet brothel. Pinto plays Rashmi, a hardened prostitute who introduces the teenager to the reality of her new life.
Rashmi is beautiful, brittle and untrustworthy, but Pinto says we should not be too quick to judge women in her situation: "The ones who have landed in this hell have been betrayed and it's the worst sort of betrayal, sold by the husbands or fathers they trusted."
Love Sonia was inspired by the real story of a girl rescued from a shipping container in Los Angeles. In the film, Sonia and her fellow prostitutes are trafficked to Hong Kong and to America into the clutches of men prepared to pay high prices for very young girls.
"It makes you wonder, in a progressive society like America or in the UK [where human trafficking is said to be worth more than £100 million ($190m) a year], what is the Government really doing about this problem?" says Pinto. "There will only be a supply if there is a demand.
"We have to talk about the issues driving this."
- Telegraph Media Group
