Kathryn Hunter: Gender bender

She has played Richard III, Pantalone and King Lear. Now she's tackling an 18th-century cross-dressing doctor. Is there something Kathryn Hunter isn't telling us, asks Heather Neill. Or does she just like a challenge?

'I think I'm brave, playing men on stage. She did it for life - 40 years in the British army, of all places!" Kathryn Hunter is talking about Dr James Barry, aka Margaret Bulkley, the 18th-century surgeon who spent her entire adult life in disguise. Already famous for her male roles, Hunter is preparing to play the Irish cross-dresser in Whistling Psyche, Sebastian Barry's new play at London's Almeida Theatre.

For those who know Hunter's work, the choice will come as no surprise. Previous characters have included a nine-year-old autistic cancer sufferer (in Lee Hall's Spoonface Steinberg), a loquacious passenger in the back of Timothy Spall's cab in Mike Leigh's All or Nothing, and Shakespeare's toughest monarchs (King Lear at Leicester in 1997 and Richard III at Shakespeare's Globe last summer). Her present director, Robert Delamere, didn't choose her for her experience of playing male leads, however, but for the "extraordinary physical daring and depth of enquiry" she brings to her acting, useful qualities in exploring this unique character "trapped", as Delamere puts it, "by her own invention". Hunter, he says, "is a transformer, thrilled by a challenge from left-field", although in this case, despite appearances, the transformation is more psychological than gender-driven.

Kathryn Hunter, 47 ("just!"), is diminutive - a mere five feet tall - with expressive brown eyes and the olive skin of her Greek ancestry. Born Aikaterini Hadjipateras in New York, the daughter of a shipping magnate, she came to England at the age of two, went to school in London and then onto RADA, and changed her names, anglicising the first and borrowing the second from a boyfriend. Just now she has a neat cap of crisp dark curls. "It's not quite right yet," she says of Dr Barry's coiffure. Hunter is a stickler for detail: to play Lear she shaved her head and adopted a wispy beard.

Lee Hall, who has worked with her on a number of projects, testifies to her thoroughness: "She researches like a mad woman, then throws herself into the part with abandon. She'll grasp what the play is about then go mole-like, blindly finding a way in. Intellect and instinct meet and you can't help being affected by that." But where did this dainty, feminine person acquire the daring to act men - heterosexual, authoritarian, even brutal ones at that? It all began at school when, aged 14, she became fascinated by King Lear and fantasised that she would one day play him. "I became totally obsessed with Lear's journey, his courage to go out into the storm. In fact, I think my parents received a letter to the effect that maybe Kathryn shouldn't spend quite so much of her time writing 35-page essays about King Lear." Her chance came aged 40, when the director Helena Kaut-Howson invited her to fulfil this ambition and she accepted the challenge. "I knew it was outrageous and my nerves tingled, but as an Aries I'm very impulsive."

Obsessive, then, and meticulous since schooldays, her professional background combines the study of classical texts with the physical exuberance of Complicite: she won an Olivier Award in 1991 for her riveting portrayal of the terrifying Clara in that company's production of Dürrenmatt's The Visit at the National Theatre - despite being "30 years too young" for the part. Her adventurousness in choosing roles she puts down to Complicite's openness. It was no problem that, in Commedia, she found it more interesting to be the old man Pantalone than the girlish Columbine, or that she relished playing the Old Shepherd in The Winter's Tale. Given this background, Lear was less strange for her than it might have been for another actress. And after that, Richard III didn't seem such a surprise.

But for now, Hunter is so taken with Barry that other topics don't get a look-in for most of the interview. She produces a biography of Barry, Scanty Particulars, by Rachel Holmes: "Look at this, definitely a girl," she says as she points to a photograph of the young Miss Bulkley. "Then, look at this..." She turns to two further portraits which could be of a stern Victorian patriarch not unlike, say, Brunel: "Much more masculine than me."

Nevertheless, Barry's appearance was remarked on, says Hunter, because "he" was unusually small. "I think she got away with it because a) she was a good doctor and surgeon and b) she adopted a tactic of, rather than hiding in the shadows, emblazoning herself on society. She loved parties."

A reformer 30 years before Florence Nightingale, she received little recognition for her contribution to medicine and, in Sebastian Barry's two-hander, is bitter and disappointed, recalling her life in an elegiac but compelling stream of consciousness. In a limbo-like waiting room around 1910, when both are dead, Bulkley, still impersonating a male doctor, meets the ultimate nurse, Nightingale herself, played by Claire Bloom.

Historically, they met once, at Scutari, where Barry was unexpectedly less than supportive of Nightingale, no doubt allowing animosity to cloud her judgement. In Whistling Psyche, each lonely and isolated, they speak in monologues, but gradually each acknowledges the other. "They are there," says Hunter, "because they can't bear to let go. This is a hook we can all relate to: the play asks questions about what constitutes a meaningful life."

There may be a family connection between the playwright and James Barry (who adopted her mother's maiden name) but, says Hunter, the inspiration to write about the character came from reading an earlier biography 25 years ago. "It took him that long because he didn't want to get bogged down in historical detail. Then he wrote it instinctively." The facts are extraordinary enough to excite any writer. After a childhood spent in poverty in Ireland - her father disappeared and her mother was confined in an asylum - Margaret acquired the patrons - including Edmund Burke - who had supported her uncle, a painter. Possibly at the suggestion of one of them she disguised herself as a man to train as a doctor, something which would have been impossible for a woman at that time. She was posted to different parts of the Empire where she treated the great and the good, but also spent much time with lepers, prisoners and the mentally ill, advocating just the kind of reforms in hygiene, water supply and diet which later made Florence Nightingale's name in the Crimea in the 1850s. "Nightingale was," observes Hunter, "in the right place at the right time, whereas Barry practised in far-flung colonies not in the headlines."

Her personal life did not go unnoticed, however. While in South Africa, Barry had an affair with the governor, Lord Somerset, which resulted in a secret child who died at birth. Somerset, accused of sodomy, faced a scandal which was particularly difficult to face down. Barry nursed him when he was sick, and risked court martial by refusing to leave Somerset for a posting in Mauritius. It was, Hunter believes, "a deeply felt love that, as Sebastian says, went beyond England and history."

Fans of Sebastian Barry's earlier work (The Steward of Christendom, Our Lady of Sligo) will not be surprised to learn that the speeches are long and dense with imagery. Poetic and full of anecdote, they make vivid reading but look a nightmare to learn. How does Hunter do it? She had memorised the entire role before rehearsals began, and then had to learn the cuts as well. "I read it hundreds of times and tried to see the images in the text, but in this case it could be a huge diversion because they come so thick and fast. Sebastian talks like he writes, in huge arcs - some of the sentences are 15 lines long! And I became obsessed with that dog. What does it look like?" Barry had a series of poodles, all called Psyche. Hunter says the name is no accident. "The play begins with someone looking for a dog who is also searching for his/her lost soul."

Hunter admits that when she first read the piece she wondered if it was sufficiently theatrical: "There are no murders or dramatic events, but you realise that there is another kind of action. The seduction of the poetry challenges you to see that it is politically passionate, that there is a visceral, political nerve going through this apparently poetic body. It is a play about the nature of Irishness, what Sebastian describes as the black man, the outsider." She learned a Cork accent with the help of voice coach Joan Washington, but "put it away", having come to the conclusion that Barry's transformation would have been complete, although some of the sounds may well creep in. "The play is about the conflict and interdependence of England and Ireland and about Empire." Hunter sees Nightingale as almost a mascot of Empire, while Barry was a rebel: "Her existence [as a doctor] depended on the Empire, yet she was its fiercest critic. She was a disturbed person, bitter and full of demons, bad-tempered and outrageously critical. I think that came partly from fear of being discovered." In the play she is a wonderful storyteller, but Delamere and Hunter have spotted the danger in this: "Rob said, 'Kill the raconteur.' We must go for something much more lived."

Hunter's sympathy with Barry - a woman who can convince as a man - is easily enough understood, but last year she was making a case for Richard III as someone who shared her wicked sense of humour. She can combine tragedy and comedy in a sentence. Lee Hall says she has the ability to make you laugh at things you never thought you'd find funny, but often uses comedy for a serious purpose. Her own life has not been all comedy by any means: she suffered depression in her adolescence and even attempted suicide while a student at RADA. She threw herself out of an upstairs window and was told she would never walk again. She's not keen to dwell on this, anxious to avoid "a sob story", but the resulting "wonky" arm and slight limp were turned to advantage for Richard III, while her tiny Katherine whirred about the Globe stage like an angry hopping wasp in The Taming of the Shrew. Everything is grist to her character-mill.

These days her personal life is settled and happy: she has lived with Italian-born actor and clown, Marcello Magni, for some 16 years, and they manage to work together fairly often - each has directed the other. They recently returned from a trip to India: "I've always wanted to take Marcello. I love India. One of my first jobs was a British Council tour there on which I played Jessica in The Merchant of Venice."

This year's trip was more than a nostalgic wallow, however. Hunter has been researching the life and "volumes" of works of Dr Ambedkar, a reforming lawyer who drew up the constitution of free India. He is someone else whose history has been obscured, which is how his name came up in the context of Barry's story. Ambedkar championed the cause of the untouchables, disagreed with Gandhi on matters of policy and converted from Hinduism to Buddhism.

Hunter is combining with the British Asian theatre company, Tara Arts, who are workshopping her research with the aim of turning it into a play. She is more interested in characters than "issues", but volunteers that this could be an instructive study of leadership. Already known as actor and director, she may soon add writer to her portfolio.

Buddhism has personal resonances for her, too. She says she has always been interested in it and while she won't confirm anything as definite as conversion, has been learning to meditate at the Buddhist Centre at Bethnal Green in London. "Yes, it helps. I'm too agitated otherwise. It's very practical, not about airy-fairy things like staring at a candle flame."

These are private matters, however, and she hesitates when asked for details of her own spiritual search, but the idea of the lost soul, the Psyche of the title, is one she returns to in a description of a visit to Sebastian Barry's home in County Wicklow. She and Robert Delamere flew to Dublin the week before rehearsals began. "There were gale-force winds and the pilot found it difficult to land. Passengers were calling on Jesus and being sick.

"I've always thought it silly before when people applauded a landing, but this time everyone applauded with huge enthusiasm." Later they went to a dogs' home with Barry. "Sebastian had saved a hunting dog, but it was going after sheep so he had to give it away. There we were in the dogs' home in a howling wind. It seemed like a sign. Souls are not just ethereal, they exist in a howling wind, in rage and despair."

'Whistling Psyche': Almeida, London N1 (020 7359 4404), previews from Friday, opens 12 May, to 19 June