Deborah Findlay is the actress of choice for top writers and directors, and yet she is most famous for not being famous. David Benedict met the unassuming leading actress on the eve of her latest play.

You'd have to be very sad, bad, or both to spend rehearsals thinking, "Will this win me an award?", but like it or not, the odd glittering prize doesn't do an actor's career any harm. The calm, coolly intelligent Deborah Findlay is probably the last person to waste valuable rehearsal time considering such nonsense, so she was probably more surprised than anyone when her heart-wrenching performance as Hilda, the forbearing wife of the painter Stanley Spencer in Pam Gems's play Stanley, won her a richly deserved Olivier award.

Yet the fact that she was last year's Best Supporting Actress, when Antony Sher as her on-stage husband was named Best Actor, is a typical twist of fate for Findlay, who is without doubt one of the finest actresses of her generation and probably the least known. Not that she is the slightest bit unhappy with the situation. "The Olivier has given me a bit more recognition," she concedes, with a shy smile. And about time, too. She has played leads at the RSC, lit up West End revivals, toured the country with Joint Stock, been quietly devastating on television, and anyone who's been to the Bush or the Royal Court in living memory will recognise her from any number of shows. Unforgettably, she played twin roles as the wryly comic Isabella Bird and tough but tender Joyce in Max Stafford-Clark's famous production of Caryl Churchill's Top Girls, which netted her an Obie Award in New York, but nothing here. How come she is the profession's best kept secret?

Anthony Minghella, who cast her in the leading role in his semi-autobiographical TV trilogy about marital breakdown, What If It's Raining?, back in 1986, and then again as Juliet Stevenson's sister in Truly, Madly, Deeply, is unequivocal in his praise. "She has built up an incredibly impressive body of work. Her quietness distinguishes her. She is not a pyrotechnics actor. She leads with self-effacement." And that's the problem. You don't get "Hey, look at me!" acting with Findlay but, sadly, it's the flashy stuff that people remember.

Too many actors readily assume a faux naivete and whisper to interviewers that they "really don't want a Career". In fact, most acting careers consist of taking what is offered. Findlay, however, is genuine about her relatively unglamorous choices. Faced with the question of why she isn't a household name, she blames herself. "I think I'm shy... no, wary of all that publicity," she replies, rather reticently. "I've just done the work that has interested me. I have to be excited by the piece." It's striking that she immediately talks about plays, not roles. Only later does she talk about needing to connect with a character in some way. "It's something to do with heart," she says, thoughtfully.

If that gives you the impression of a woolly minded sentimentalist, think again, though, by her own admission, she never trained properly. "I learned my craft [a favourite word] along the way. I've always played. I've always made-believe. I didn't know how you could be an actor, but I just loved playing. Pretending to be other people."

She stops herself. A smile whips across her sharp features and she laughs, skittishly, "I suppose that says rather a lot about me."

Instead of going to drama school, she read English at Leeds University in the late Sixties, where Jack Straw was President of the Union. Even back then, her talent stood out. Fellow actor Stephen Ley cast her as Georgina, the mad Salvation Army officer in Edward Bond's Narrow Road to the Deep North. "It was the best performance anyone had seen at the university," he recalls, quick as a flash. After Leeds, her next audience was a primary school in Giggleswick, where she worked as a teacher. "She was very dedicated, but she had this terrible conflict between whether to teach or act," remembers Ley. "When she finally decided to leave, it gave her a strong impetus to get on." The pair of them joined up with fellow graduate David Stafford (now a journalist) and became Charlie's Ritzy Cabaret. She was Ruby Dubois, in A-line skirts and little red tops with bunny fur trim." They spent an entire season at Bracknell writing and performing hour-long cabarets on different topics each week. Ley believes her strength lies in the fact that she's basically a comedienne. "She sees a character's comic potential. That's why she's good, she's always on top of a role."

He's not making light of her gifts when he adds, "she's interested in giving people a good time, in entertaining them."

It's a surprising diagnosis for an actress famous for suffering on stage and screen. Hilda in Stanley suffered from page one. The nearest she's got to prime-time viewing was playing a distraught mother in Casualty, for goodness sake. "I know," she pleads. "I love comedy." There's an almost wicked glint in her eye as she admits that she knows she can make people laugh. It's true. Her screaming (and screamingly funny) performance in The Clandestine Marriage, opposite Nigel Hawthorn, was likened to a 19th- century version of Violet Elizabeth Bott. Years ago she fronted the band in Martin Duncan's legendary Stratford East panto A Night in Old Peking as lunatic Bloomsbury-eccentric Dame ffrog. "The whole thing about theatre is that it's live," she insists. "With comedy, you know when an audience is held. I think it was Edith Evans who said, 'The great skill is not to make people laugh, but to make them laugh when you want them to.' You know they're going to have a really good time in a minute, and it's great!"

Paul Godfrey directed her in his Benjamin Britten play Once in a While the Odd Thing Happens. "Audiences have an automatic empathy with her. Commonly, you see actors acting. When Deborah comes on stage you suddenly feel there's a real person present because she has a wonderful gravity. It's not like a character talking. She takes a writer's language and makes it her own. There's nothing mystical about this, it's just that she has the most amazing verbal dexterity, more than any actor I've ever worked with." Minghella agrees. "She's completely earthed, grounded from the text. As a writer you long for people like that. She was designed for Ibsen and Chekhov, for the way she conveys absolute eroticism, sadness, the missed opportunity... what's lost."

That last quality makes her the perfect choice for her latest role as the pilot searching for a missing child in Ellen McLaughlin's moving Tongue of a Bird. "It's very arresting, it really grabs you," she explains, her dark eyes gleaming. "Ellen is American and I've always thought there's a different quality to American writing. The way they use language is very, very different. These beautifully crafted sentences come at you and you really have to take it on board, go for it and not be frightened."

The play also allows her to do what she does best: to create a still centre at the heart of a complete and contradictory character. It's that stillness that draws audiences to her. Unsurprisingly, Findlay chooses to focus on the writing, its energy. "The challenge for me is to embrace that energy without being self-indulgent, but without holding back. It's a leap in the dark. You have to take a deep breath and say to yourself, 'Well, I'm gonna try.' " Her apprehensive laughter fills the air, perfect preparation for a play about the fear of flying.

'Tongue of a Bird' is at the Almeida, London N1 (0171-359 4404) to the end of November.