Three-time Oscar nomineeCarey Mulliganis its heart, providing a grounding presence between the grumpy musician and lovable weirdo.

Vogue: This film was based on a BAFTA-nominatedshort from 2007.

Where did the idea for the premise come from?

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Carey Mulligan and Tom Basden inThe Ballad of Wallis Island

We tried to get the balance right, where you didnt just hate everyone concerned.

What was it like to revisit these characters all these years later?

Tom Basden:I definitely think weve finally got to the right age to play these characters.

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Basden, Mulligan, and Tim Key inThe Ballad of Wallis Island

We wrote it from the perspective of being in our mid-40s rather than our early 20s.

Carey, what drew you to this role?

Did you know Tom and Tim before this?

Carey Mulligan:I didnt know them personally, but I knew their work and was a big fan.

It was one of the best scripts Ive read, just lovely andsofunny.

It looked at the fact that music plays such an enormous part in our lives.

Tim, you play a compulsive chatterbox.

How much of that was improv?

Carey organically fell right in with that, elevating all those rhythms.

Tom, you wrote all the songs in the film, some 25 songs in total.

How did you manage that?

Basden:Ive been writing songs for the film since we first made the short.

That made the process of songwriting a lot easier.

All youve seen up until that point is him being quite guarded and grumpy and unemotional.

I was excited that the music could do something particular for the story, that it wasnt just incidental.

Carey, what did you think when you first heard the songs?

And what did your husband think of the songs?

Basden:Oh, dont ask her that!

Mulligan:[Laughs.]

I love the songs.

I mean, Raspberry Fair is an instant classic.

The songs were a huge part.

Some are sweet, others are quite devastating.

A song can take you somewhere, and so many of the songs Tom had written had that quality.

Mulligan:We really need that album, actually.

Key:Yeah, I think so.

Basden:[Laughs.]

I might need another 18 years to really master the kind of David Guettastyle pop collab music.

Sadly, those songs dont exist.

You just have to imagine them, and whatever youre imagining, thats exactly what they sound like.

Carey, youve sung in films before and have also said you find it terrifying.

How do you overcome that fear?

Mulligan:Singing in a live environment I cant get my head aroundthats so scary to me.

Its just so exposing.

If your voice fails you or you go slightly out of tune, its weirdly embarrassing.

With singing, it feels like an enormous failure to do it wrong.

Why do you think this is the right time for this?

A lot of people have said the same thing: I really needed this movie at this time.

Its quite a tough time, and theres a lot going on thats difficult to cope with.

Basden:Maybe people are responding to it because that kind of film is in short supply.

Theres also something to be said for things being timeless and having a self-contained fairy-tale feel.

It starts with someone arriving at an island and ends with that person leaving the island.

Therefore, it can exist at any time.

Key:Id have the Beatles on the beach.

Basden:Acoustic set?

Key:Thats something wed have to negotiate.

Im sure we could organize generators.

The tricky bit is getting them to the beach.

Thatd be nice, wouldnt it?

Might be a bit loud.

Mulligan:Andrea Bocelli and Celine Dion belting it out at The Gorge in Washington.

Basden:The reverb, though.

Mulligan:Would be out of control.

But I stand by it.

This interview has been edited and condensed.

The Ballad of Wallis Islandis now in select theaters, playing everywhere April 18.