Saoirse Ronan: On set with Brad, Keira and Michelle

First things first: it is pronounced “sur-shuh”, and means “freedom”. Soon, though, Saoirse Ronan’s name will be tripping off our tongues as lightly as Keanu, Keira or Cillian. The 13-year-old schoolgirl from Ardattan, County Carlow, is a regular fixture of this year’s acting shortlists for the Baftas, the Oscars, the Golden Globes and the London Film Critics, to name but the major ones.

The plaudits are inspired by Ronan’s striking performance in Atonement as Keira Knightley’s kid sister: a solitary, eerily self-contained girl on the cusp of adolescence who tells a devastating lie out of a mixture of confusion, jealousy and nascent, unadmitted sexual feelings. Most unusually, the director Joe Wright cast the young actress first, rather than the more established stars, Romola Garai and Vanessa Redgrave, who play the same character in later life.

Everyone who has seen Atonement will remember Ronan’s elegant oval face, with its fresh complexion and startlingly pale, clear blue eyes. She looks like a young Vanessa Redgrave – or perhaps one should say that Redgrave looks like an older version of her. Even before the awards, sharp-eyed critics had spotted her. The New York Times described her as “remarkably poised”, while the LA Times singled out her performance as “exceptional”.

Speaking this week from a film set in Wellington, New Zealand, Ronan comes across as bubbly, down-to-earth and full of self-mocking humour – completely unlike that solemn character, in fact.

“Every time that I find out I’ve been nominated for something, I’m in bed,” she says. “It’s not very handy being out here when all this is going on, though it’s still kind of nice to be away from it as well. We are getting a bit worried about what I’m going to wear. There are a few designers, or whatever you call them, sending over dresses and we need to get that sorted. I’ll be wearing something, anyway. I won’t be going in my knicks.”

Ronan spent her childhood on the road, as the daughter of the actor Paul Ronan. One of her earliest experiences was being handled as a baby by Brad Pitt on the set of The Devil’s Own.

“He just picked me up and said, ‘Oh, I don’t like this kid, I’m giving her back to her parents!’,” she says, laughing. “It wasn’t like we had this special bond or anything.”

Did she always want to act? “I used to play with my dolls and give them different accents. My Polly Pockets would have affairs with each other – things that probably a seven-year-old shouldn’t have them doing. But it wasn’t until I did Atonement that I knew I wanted to take it up seriously.”

Ronan got her start with regular roles in two Irish television series, The Clinic and Proof. But recently she has been moving in exalted international company – and that practice with the Polly Pockets has come in handy, since none of her roles has allowed her to use her natural Irish brogue.

She played Michelle Pfeiffer’s daughter in an American romantic comedy called I Could Never Be Your Woman, and Catherine Zeta Jones’s Scottish daughter in Death Defying Acts, a period drama about Harry Houdini (neither film has had a UK release yet). “It was definitely a change from Irish telly. But at the end of the day, there’s nothing to be starstruck about. These are just ordinary people and we just happen to do the same job. We could be working in an office.” Some office.

She also has plum roles in two big forthcoming films. The first is City of Ember, an adventure fantasy co-starring Bill Murray. “We shot it in Belfast in the Titanic Quarter, where they painted the Titanic. We transformed it into a set…” She pauses, in case that sounds a bit self-important. “Well I didn’t. I don’t want to take all the credit.

“Bill Murray was brilliant and so funny. When we were shooting a scene, he would add in extra lines to make me laugh. He was always making fun of people, just messing, but I always fought back. I’d laugh but I’d make fun of him too.”

Ronan is in Wellington for Peter Jackson’s adaptation of Alice Sebold’s The Lovely Bones, in which she plays the narrator of the story, a young girl who is raped and murdered and observes the effects of her death on her family from the afterlife.

“We’re shooting Heaven in New Zealand,” she says. “It’s the perfect place because it’s so beautiful here. When you hear the story, you think it’s going to be so dark with everyone crying all the time. But I have to say it’s not a depressing film.”

After that, she plans to go back to school in Ardattan. But first there are all those glitzy awards ceremonies in her diary. “Oh God, I’m so excited. You see, I watched the Oscars every year at home on an Irish channel and the reception was fuzzy because we were in the country. Every now and then, it would be: ‘The winner for best actor is…’ and then the screen would go all grey. It’s kind of surreal that I’m actually going to be there this year.”

© Telegraph.co.uk