HOW a 'funny tape' convinced iconic directors that Mulligan was ideal star for new movie.
BLESSED with a dulcet singing voice and hired to play an aspiring chanteuse in the new Coen brothers film Inside Llewyn Davis, it might seem a natural progression for Carey Mulligan to dip her toe into singing.She could, after all, lend her honeyed tones to husband Marcus's band, Mumford & Sons.
"Oh no," she says, laughing at the suggestion. "I only sing for jobs."
Modest though she might be about her talents, the unaffected 28-year-old had the surprise honour of terrifying the Coens with her audition.
"Carey was an actor we wanted to work with. We'd seen her in An Education and she was really great in that. We weren't thinking about her as a singer, but she can sing," reveals Joel Coen.
"We saw a lot of actresses for the part but Carey sent us a tape and it was very funny.
"Funny because she was angry," adds his brother Ethan. "It was a really angry reading of the scene with an American accent, and we were a little scared of her. And surprised. She had just done a movie with Oscar Isaac in which she couldn't have been sweeter."
That film was Drive, fronted by Ryan Gosling, which saw Mulligan and Isaac, who also stars as the eponymous hero in Inside Llewyn Davis, play an unhappily married couple.
It's a role that's helped to seal Mulligan's reputation as a leading light in Hollywood.
And it's no wonder, looking at her CV, that she's received such attention. Born in London in 1985, her silver screen debut came as Keira Knightley's sister in the 2005 remake of Pride And Prejudice, in which Knightley played Elizabeth Bennet.
She landed the role after learning about it from Downton Abbey writer Julian Fellowes, who'd delivered a lecture at her school.
It was certainly a commendable first acting job, but it was as clever A-level student Jenny in 2009's An Education, that Mulligan really showed off her acting muscle, gaining herself an Oscar nomination and a Bafta win for her efforts.
Since then, she has had her fill of blockbusters, including playing leading lady Daisy in last year's The Great Gatsby. She has also starred in indie hits, such as 2010's Never Let Me Go (which saw her reunited on screen with Knightley) and edgy, hard-hitting drama in the form of Steve McQueen's Shame.
And yet despite her Hollywood status, the British rising star – who cites fellow Brits Emma Thompson, Kate Winslet and Samantha Morton as her acting heroines – admits she was overwhelmed to land the part of no-nonsense singer Jean in Inside Llewyn Davis.
"It was amazing, I wasn't expecting [it] at all," says the actress, who is looking chic in a monochrome blouse.
"I was filming Gatsby when I got the script and did the audition tape in Los Angeles. I had fallen in love with it, but was completely unaware that there was any chance of me getting the job."
A long-time fan of the Coens, famed for films like No Country For Old Men, The Big Lebowski and Fargo, Mulligan was keen to impress.
"I felt immense amounts of pressure to do it well. I was so, so happy when I got the call," she says.
The film, which Mulligan calls a "Valentine to folk music", follows a week in the life of failing folk singer Llewyn Davis, who lives in New York in the 60s.
Mulligan's on-screen husband, Jim, is played by celebrated singer Justin Timberlake and her real life spouse Marcus, who she married in 2012, was the film's associate music producer.
Though she sang in Shame, she confesses that she was apprehensive about blasting out a number with Timberlake.
"I'm always very nervous about singing in front of people," she says.
"Singing, for me, seems to be the most nerve-racking thing to do. And when you're surrounded by actual musicians like Oscar and Justin, it's even worse."
Mulligan is insistent that she "got away" with performing in the scene by trilling away in the background, but jokes that she told the Coens she could sing "to get the job!"
While the other cast members "jammed" away with their guitars during breaks in filming, Mulligan just tapped her feet on the floor. "That's about as much as I got involved."
The actress may be soaring up the ranks amid Hollywood's leading ladies, but she's still conquering tinsel town on her own terms.
"I lived in New York for a while," she explains. "I did a couple of jobs and some plays there, so I've been there for six months at a time and I love it.
"But I moved home a couple of years ago because I love being near my family."
Inside Llewyn Davis is released on January 24