Katrin Cartlidge who has died aged 41 (of complications from pneumonia and septicaemia) was one of the most fearless and passionately committed performers on screen and stage to have emerged from Britain for years. From her first appearance as Lucy Collins in television's Brookside, through 25 films and many stage appearances, her career was remarkable.
An early screen appearance was as Sophie in Mike Leigh's film Naked (1993), which was the beginning of a profound collaboration with Leigh. This was recognised when she won best cinema actress in the Evening Standard Awards for her inventive creation in his film Career Girls (1997). As her career progressed, the range of work available to her was enormous.
But it was her choice of the work that demonstrated her unique qualities. She worked for the Danish director Lars Von Trier in Breaking The Waves (1996), when few in Britain knew about his films. She worked with the unknown Macedonian director Milcho Manchevsky in the Oscar-nominated Before The Rain (1994), which won the Golden Lion in Venice that year. In the Oscar-winning No Man's Land (2001), the first film of Bosnian director Panis Tanovic, she played a justice-seeking journalist. For Lodge Kerrigan in New York, she played an Irish immigrant working as a call girl in Clare Dolan (1998).
As a result of her instinctive good taste, determination to recognise quality over hype, and belief in the process of cinema as well as the product, her opinion was constantly sought; she was asked to be on the jury of film festivals, and asked for advice by first-time directors. Even hardened producers would seek her out for her take on the viability of a project. She was unafraid of saying what she believed in, of making herself heard in an art form that too often - and she believed to its detriment - was cued by money and celebrity. Her interest was in the redemptive power of art and her own art was inspired by a knowledge of sculptors, poets, and musicians, as well as movie-makers.
Cartlidge was born in London and educated at Parliament Hill School for Girls in Hampstead. At the beginning of her career in the 1980s, she did hundreds of readings at the Royal Court, and was picked by Peter Gill to perform at the National Theatre in Apart From George, by writer and director Nick Ward. She had started her career as a dresser for Jill Bennet in the number one dressing room at the Royal Court, which she herself most recently occupied when appearing in Boy Meets Girl.
Her stage work seems to have been overshadowed by her films, but from her first appearance, naked, at the Riverside Studios in the 1980s - she described it to me hilariously - to her last performance at the Royal Court in 2001, her stage performances were characterised by quiet integrity and total commitment.
She worked with enormous humour and an intensity extraordinary because it was so light, positive and considerate of others. I know this because between 1999 and 2002 she worked on our play Mnemonic, with me and with five other actors, for the theatre company Complicité. She was its motor and its energiser, as she was with any project she worked on, as the play voyaged from Huddersfield to New York.
She believed profoundly in social justice and political reform. Always articulate and sharp, she was scathing of elitism and was a furious opponent of the political status quo throughout the world.
She was steadfast, especially as a friend, and always there for all of us. We sought her out, as people did in her work, for her instinctive sense of what was right, her sense of direction, advice, humour, company, and her love.
Those of us lucky enough to know her as a friend became her family; she drew her own inspiration from her love of her family, of her parents, sister, brother, and her partner Peter. Her loss to the cinema is colossal. Her loss to her family is even greater. We were lucky to have her for the time we did.
· Beeban Kidron:
Katrin had a reputation for giving everything to her comrades. Throughout her creative life she found herself, again and again, in extreme situations, and wondered each time why it was happening again. To which the answer was that she was extraordinarily brave, interested, and complicit in helping people find the edges of their creativity and the extent of their expression.
She worked off a moral core and a commitment to her craft which rendered her forthright and often contentious. She was famously strong, but paired with her strength was a fragility, a translucency, and an empathy that was at the core of her talent.
· Katrin Cartlidge, actor, born May 15 1961; died September 7 2002