For those who remember, he was the young boy who gets the girl in the film Love Actually. For those who don't, Thomas Sangster may yet become a household name. The sixth-former from south London, the Guardian can reveal, has been chosen by Steven Spielberg to be his Tintin for a three-movie adaptation of the boy reporter's adventures. The trilogy is likely to give the 17-year-old the same profile as Daniel Radcliffe, aka Harry Potter, or Elijah Wood, who shot to international stardom as Frodo Baggins in the Lord of the Rings series.

More than 200m copies of Hergé's Tintin books have been sold around the world; fans tend to be devoted, if not obsessed by the character, his faithful dog Snowy and his perpetually frustrated friend Captain Haddock, an endearing drunk.

Spielberg has been working with Peter Jackson, director of The Lord of the Rings and King Kong, on how to bring Tintin to life. Now the production has taken another significant step with the casting of Sangster, alongside Andy Serkis, who played Gollum in the adaptation of Tolkien's books, as Captain Haddock.

Both actors spent a week in Los Angeles before Easter running through scenes for Spielberg and Jackson; work begins in earnest in September, with a view to releasing the first film in 2010.

Sangster admitted to the Guardian that he had not read Tintin until a few days ago. "But I've always loved the cartoons. I never saw the books because I was never that big on reading. When I was really young I watched some episodes and loved it.

"You can really escape into this fantasy world ... I love cars and aeroplanes and stuff, any car or any aeroplane or any gun that was ever used in Tintin would always be real, an exact copy of it so if it was a car it would be a Citroen and if it was a gun it would be a Luger.

"Tintin is like a super boy scout. He knows how to fly these things. He knows how to drive these things. It's just like common sense: he jumps in and goes, he doesn't need to think about any safety, he just goes where he pleases. For such a small kid he's very good at beating people up and, being a cartoon, nowadays you know, there's all that 'we can't be violent'.

"Tintin would hit people over the head with bottles and shoot people. He probably wouldn't kill them but he'd shoot them in the shoulder. He was cool."

Many people will recognise Sangster as Liam Neeson's son in Richard Curtis's Love Actually or the oldest child in the care of Emma Thompson's Nanny McPhee, but his CV includes roles of varying sizes in 13 films. He is also the voice of Ferb in the Disney Channel's cartoon series Phineas and Ferb and has been on TV in programmes including Doctor Who and Stig of the Dump.

A child of theatrical parents - his dad Mark is currently starring as the mad hyena in The Lion King - Sangster is soon to undertake A-levels in art and media studies. He works part-time at a local garage when he's not at school or, as he is at the moment, rehearsing for the latest Jane Campion movie.

Sangster's agent originally sent a tape to Spielberg as part of an audition for a mini-series of Stephen King's The Talisman, which never got off the ground. Spielberg saw the tape and realised he had found his Tintin.

All the regular characters are expected to be in the new movies, including the oafish detectives Thomson and Thompson and the virtually deaf Professor Cuthbert Calculus.

But it is not yet known which of the 23 Tintin stories will be filmed. And while Spielberg will direct one and Jackson one, it is still not known who will direct the third.

They will be filmed back to back in the US and New Zealand, using the latest 3D technology, which is regarded within the industry as the next frontier of moviemaking.

Spielberg said recently: "We want Tintin's adventures to have the reality of a live action film and yet Peter and I felt that shooting them in a traditional live action format would simply not honour the distinctive look of the characters and world that Hergé created.

"The idea is that the films will look neither like cartoons nor like computer-generated animation. We're making them look photo-realistic, the fibres of their clothing, the pores of their skin and each individual hair. They look exactly like real people - but real Hergé people."

Tintin has become a worldwide industry, controlled by the Hergé Foundation, with limited edition vinyl toys proving particularly lucrative. The TV animated series of Tintin produced in the early 1990s has proved the most popular screen version of Tintin, while a stage version by British director Rufus Norris at the Barbican in 2005 transferred to the West Wnd and toured.

Hergé, who died in 1983, was briefly the subject of a race row last year when the Commission for Racial Equality said Tintin in the Congo, written in 1930, should not be sold in Britain.

Hergé admitted during his lifetime that the Congo book and Tintin in the Land of the Soviets, both with unsubtle racial stereotyping, were "youthful sins".