Danny Boyle, who has directed some of Hollywood's best known names like Leonardo DiCaprio (The Beach) and Cameron Diaz [Images] (A Life Less Ordinary), never thought he would have trouble finding a teenager to play the lead role in Slumdog Millionaire.

"I had to break a promise I had made myself to cast all the actors in the film in India," he said. He was happy to sign on newcomer Freida Pinto, who grew up in Mumbai. She plays a ravishing young woman risen from the slums, become a mistress of a rich man but still looking for real love, Boyle says. But the director, best known for his films 28 Days Later and Trainspotting, confesses he found the young Bollywood actors, not to forget the newcomers he interviewed, obsessed with the gym.

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"The young actors start their day in the gym and some of them I believe even spend more than six hours there once or twice a week," he, said soon after the public screening of the movie ended with prolonged applause at the ongoing Toronto International Film Festival. "They have so many muscles they find it difficult to lower their arms. Now, how can they can play an underdog from the slums, who is about to become a millionaire in the quiz show?"

Had he gone on searching for months, he might have found a local talent to play the lead but he had just a few weeks to do the casting.

"So I broke my promise but even then, I wanted to find someone of Indian heritage either in England [Images] or America," says the London-based filmmaker. "My 17-year-old daughter came to my rescue and showed me Dev Patel, who is in racy but well regarded British TV show called Skins that has a cult following."

Dev steals many scenes from the flamboyant and intensely jealous host of the television quiz show, played by the veteran actor Anil Kapoor [Images]. The film is loosely based on Vikas Swarup's novel Q and A.

"Dev and I soon discovered that we were on a similar journey in this film," Boyle continues. "Though I had read a lot on Mumbai and read books such as Suketu Mehta's Maximum City, the city was still very new to me. Each day I was learning something about Mumbai and something new about India too. It was the same thing for Dev. Though his parents are of Indian origin, he too had to undergo plenty of learning in India."

"I was excited that I was going to work for Danny Doyle," 18-year-old Dev, who was born in Harrow, England, said. "And I was excited I was going to work in India. But I was also scared."

He also said he felt enormous pressure being the only guy from London [Images], "having to play this kid who's grown up in the slums and witnessed all this. It's his past events that pave the way for his future in a way."

But with the help of Boyle and his fellow Indian artists, he steeled himself to the task. "Soon I discovered I was undergoing an amazing learning curve and I really, really began to enjoy it."

The hardest part, he said, was the accent he had to create. He didn't get a language coach or anything like that, he added. "The hard thing is, the guy who plays my brother has a totally different lingo to Freida, and she has a totally different lingo to this person," he said. "So I was constantly confused. So I just said, 'Right, I'm going to make my mind up and this is going to be my new accent.'

"I ended up just neutralising myself so it's understandable to a wider audience, which is what we were trying to get to. At the same time, it's slightly believable as someone who's grown up in that environment," he said.

This is the first time Boyle has made a film in India. "I would not have made a film in India if it had to do something about a white man or a foreigner visiting in India," he said. "I made The Beach in Thailand and the key characters in that film had no real interest in Thailand. I tried to bring out that kind of terrible attitude in the film, though I don't think I was very successful."

Boyle says he learned a few lessons quite fast about working in India. "You must learn to go with the flow," he continued. "It doesn't mean that you will not try to get things done fast but there is no point in getting upset all the time. I see these men and women, mostly the business people, from the UK, Germany [Images] and other countries, throwing tantrums at the airport when things go wrong. I suspect they throw tantrums during rest of their stay in India."

He also knew there was no reason to feel pity for the slum dwellers, especially the ones living in Juhu. He befriended many of them before he began to shoot the film and continued to seek their insights and help after the shoot started. "If at all anyone was pitied during those days, it was me," he said chuckling. "They were looking at me, all sweat and red in face, and wondering what the heck I was doing in Mumbai's slums.

"I also found them to be very generous," he continued. "And this I can say of most Indians I encountered during my stay: once they know you respect them, they go out of their way to be generous towards you, to help you in any way, and even become your moral compass, helping you navigate through cultural and religious issues."

He says he fell in love with India, "despite all its contradictions," and assures a journalist that it is not a superficial love. "I would love to make another film in Mumbai," he said. "It could even be a thriller."

Boyle believes he made a good decision in casting Dev Patel. "He makes you feel that he is somebody you can root for, believe in and belong to as he chases this dream," Boyle said. "You start caring for him in no time."