Even then, she says, she almost gave up after doing three difficult films in a row in her 20s: as well as Les Amants du Pont-Neuf, for which she slept rough in order to prepare for her part as a homeless young artist, there was conflict on-set for both Damage and Wuthering Heights, English-language films that received mixed reviews but established her international reputation. It was only her drama teacher's belief in her that stopped her from quitting. "I said acting is not for me - it's too hard!"

When she won an Oscar for The English Patient in 1997, she was genuinely surprised, and ended up giving the statue to her young son to play with. He loved it, she says, until the gold started to peel off. 'Scratch a little bit, no gold any more!' she says with a laugh, fully aware of the irony. Eventually her American publicist got her a replacement, which she kept more carefully. "I learnt my lesson!"

Still, she has never seemed seduced by Hollywood glitter. She tends to follow commercial hits with interesting independent films, or low-paid but creatively stimulating theatre productions. In 2008, at the age of 43, she spent four months learning to dance with Akram Khan before performing alongside him in IN-I, a production that opened at the National Theatre in London before setting out on a two-year world tour. "I came to that sort of by accident," she says with a shrug. Her masseuse said she should dance and introduced her to Khan's producer, "Then it all snowballed into this crazy idea of doing a collaboration."

I ask how the work has changed as she has got older, and she says she has found herself working increasingly with women. Her next film is with the Spanish director Isabel Coixet in Norway; after that, she's off to Sicily to shoot a film directed by her son's girlfriend. She makes no attempt to hide her 50 years. In A Thousand Times Good Night she wears little makeup, and the natural light shows every line - and she looks wonderful for it, with a face that is alive and full of expression. And she's certainly showing no signs of slowing down.

Since A Thousand Times Good Night, she has starred in Camille Claudel 1915, a French film about the sculptor who was confined to a mental asylum by her family, despite showing no signs of illness. Then there was the rom-com Words and Pictures alongside Clive Owen, in which she plays a painter, and created all of the pictures shown in the film herself. 'That was challenging, because my character had rheumatoid arthritis, so I had to paint with this illness."