‘When I first met the director Julian Schnabel to discuss being in his version of Jean-Dominique Bauby’s memoir The Diving Bell and the Butterfly, I remember that Julian was wearing these beautiful silk pyjamas. They were the same pyjamas that Bauby [played by Mathieu Amalric] wears in the film, and they were actually made by Julian’s wife Olatz Lopez Garmendia, who plays the role of the physical therapist Marie Lopez.

‘At our initial meeting, Julian didn’t talk much about the film – instead he talked about life. I think he’d already seen my performances in The Barbarian Invasions and Munich. He gave me Ronald Harwood’s script to take home, and he later rang me up and said, “Don’t accept any other film. I want you in my film.” I called him back and said that I loved my character, Henriette the speech therapist, although her name was different at that stage.

‘I met the real-life woman on whom Henriette was based. I imagined what it would be like to do her job and to talk to somebody who couldn’t respond to you because they’d suffered such a paralysing stroke. She says at one point in the film that this is her most difficult case and I realised how open you can be when the other person is in front of you like a new-born baby, without any defences. That’s why Henriette has that smile and why she’s so generous to Bauby, and why she’s so upset when he says he wants to die.

‘What was difficult in the film was that I had to play most of my scenes alone in front of the camera, and I could see myself in the lens. I’m best when I’m improvising with another actor, but Mathieu was sitting in another room watching these scenes. And Julian, who doesn’t speak French, didn’t really give me much direction except to say, “Do it again”.

‘A lot of people have asked me whether making the film has made me think more about my own mortality. Actually, I’ve always been thinking about that: when I was a child I’d lie on a table in the living room and pretend I was a princess in a coffin, and I’d ask adults where do we go when we die. I don’t think about death all the time now: I don’t have any answers, I just accept it, and my life feels lighter now.’
(Interview by Tom Dawson)

The Diving Bell and the Butterfly is on selected release from Fri 8 Feb.