The crowd outside the Vue cinema waiting for the premiere of Dhobi Ghat would easily have missed Kiran Rao as she walked into the Leicester Square hall. In her black coat and glasses, she could have passed off as a regular Londoner on a slightly chilly October evening. For in a world of razzmatazz and red carpets, the debutante director and wife of Bollywood superstar Aamir Khan is refreshingly low key.

The impression is reinforced the next day when we meet at the Mayfair Hotel for the Filmmakers’ Tea organised by the London Film Festival. There is almost a schoolgirl charm about her — you can picture her as headgirl carrying away all the top prizes on Speech Day. Right now, though, she is speaking animatedly about her film.

“I knew that when I made a film, it would have to be something representative of me. I wanted to make films to find my artistic voice,” says Rao, 36.

Set in Mumbai, Dhobi Ghat is a montage of the lives of the people of the city as they follow their dreams and search for love. Using an ensemble cast that includes her husband and Prateik Babbar, son of Smita Patil and Raj Babbar, the film is narrated through the eyes of two women from different social backgrounds: an Indian from America who wants to photograph the city, and a small-town girl from India who comes to Mumbai after her marriage and records her video diaries. She says she consciously made the two women the “pivot of the story” as it gave her the chance to get different perspectives of the city.

I ask her if Dhobi Ghat is an outsider’s look at the city, a Bangalore girl’s encounter with Mumbai. She is quick to correct me: “Actually I am not a Bangalore girl, I’m a Calcutta girl. I grew up in Calcutta and lived there for 18 years. Then I came to Mumbai to do my graduation. It is the kind of city that grabs you. Either you love it or you don’t and it felt like home to me, the first time I went to it. I knew that wherever I went, I wanted to come back to live my adult life here.”

Rao, who is fluent in Bengali, studied at Loreto House and La Martiniere in Calcutta, and then moved to Mumbai to graduate in economics from Sophia College. She did her masters in mass communication from Delhi’s Jamia Millia Islamia University, and knew she wanted to make films and work in Mumbai. “The film is the result of my life in the city, my friendships, my work and all the experiences I had there,” she says.

Rao adds that she wanted to make her film complex and layer it with many stories. “Life in Mumbai means 11-month rental leases and constant moving. Often when you move into a new apartment, you have to deal with the leftovers of someone else’s life,” says Rao. It is one of the themes she picks up in Dhobi Ghat. “I did not want it to be a linear narrative with a story or plot, but different people’s perception of the city. So I structured my screenplay in such a way that allowed me to have all these different narrative threads with video and photography.”

The film is no flash-in-the-pan debut. Rao studied the Masters — from Bergman, Fellini and Ozu to Ray and Ghatak — in film school, and then honed her skills working as an assistant director with Mira Nair in Monsoon Wedding and Ashutosh Gowarikar in Lagaan. It was famously during the filming of Lagaan that she met and fell in love with Aamir Khan, then married to his old sweetheart, and became the focus of the media and paparazzi.

Khan courted her for the next few years, often coming to her parents’ apartment in middle-class Malleswaram in Bangalore to meet her. They married in 2005 in a civil ceremony in Khan’s apartment in Bandra and had a reception in Panchgani for friends. It was followed by a modest reception hosted by her parents in Bangalore Club. Rao wore a Kanjeevaram sari and, despite the glare of flash bulbs, refused to exchange her glasses for contact lenses. Though a star wife, she has never felt pressured to dress or behave in any particular way and says she usually avoids parties. At home she loves to watch films, while Aamir prefers to read.

“We have a very equal relationship,” says Rao. “Because we are both in the same profession, there is a lot of mutual understanding and respect about what we do. At one time we had a rule that we wouldn’t talk about work after 9pm but that didn’t last more than a week! Both of us are fairly obsessed with our work.”

When it came to directing Dhobi Ghat, Rao initially had no plans for casting Aamir in it. He was to be just the producer. Was it true that she had insisted on a screen test and asked him to audition?

“I didn’t intend to cast Aamir,” she laughs. “I did not want a known actor for the role. For Aamir’s character I wanted a person who would blend in, be a person on the streets, and not carry the baggage of so many identities with him.”

Aamir plays the role of Arun, a brooding artist, who rejects relationships and gets drawn to the video diaries left behind in his apartment by a young Muslim woman.

“I was having trouble casting that part,” says Rao. “There was an actor I was working closely with and it wasn’t going the way I wanted. Aamir suggested he do a screen test to show me what he could do with the part. And that was it, really. Once he did the screen test, it felt like I couldn’t really look elsewhere.”

While filming Dhobi Ghat, the couple moved into the flat that is used by Aamir’s character in the film. “Work became home,” laughs Rao. “For three weeks we were actually living on a set.”

So what was it like directing her superstar husband? “Oh it was very good,” says Rao immediately. “As a producer he just green-lighted the project and took a back seat and I did all the hard work. But as an actor he is amazing to work with. The rest of my cast was entirely new, it was their first film and there was a certain excitement about that. We were all learning together. With Aamir it was suddenly that you were working with someone so skilled that you could temper the performance to the degree you wanted and go exactly where you wanted to go.”

Keeping Khan’s involvement in the film a secret from the public and the media, Rao shot the film in a 16mm format, going into the crowded locations without any hassle of security.

No doubt conscious that she has so far been branded as Aamir Khan’s wife, Rao is clearly keen to establish her own identity. While he supported her at the Toronto Film Festival, she has come to London on her own. She speaks passionately about finding her own voice.

Rao cites filmmakers Wong Kar Wei and Tsai-Ming Liang as her influences. Growing up in Calcutta, where her father was an executive at a private firm, she was never a fan of Bollywood films. Instead she revelled in Ray and Ghatak. “As a kid, I loved Sonar Kella. It scared the hell out of me, but I loved it,” she says. “But Jalsaghar is my favourite. It is a beautiful film, with amazing music.”

In Dhobi Ghat, Rao uses classical music (songs of Siddeshwari Devi and Begum Akhtar) as well as a musical score by composer Gustavo Santaolalla (Brokeback Mountain) to capture the moods of Mumbai.

Multiplexes have given her the space and artistic freedom to explore her kind of cinema. “You don’t have to fill 1,000 seats any more,” she says. She hopes the film will find a friendly audience in India when it is released in January.

“Your first film is so special,” she says simply. “It’s flawed, but it’s so much a part of you. It’s like that birthmark on your face that you don’t want to get rid of. It makes you who you are.” For Kiran Rao, being who she is, is clearly the most important thing. This star wife and filmmaker will do it her way.