Watch Hattie Morahan in Sense & Sensibility

I watch the actress Hattie Morahan swinging up a scruffy street in south London near to where she has been rehearsing her new play. She is tall, slim, dark-blonde hair pinned up any old how, with black leggings and a backpack: a modern 29-year-old about her business. And yet, once we are seated opposite each other in a restaurant, sipping mint tea, Morahan seems distinctly old-fashioned, rare, something of a throwback. Partly, it’s her features, that delicate oval face and porcelain skin; partly, it’s her reticence in claiming credit: the long eyelashes sweep down when you say you like something she has done. “Thank you, I, um . . .” Even her teenage fans are curiously decorous. When I ask if playing Elinor in the BBC’s recent Sense and Sensibility meant being recognised in the street, she confides she was “passed a note” by two shy schoolgirls in Foyles bookshop, marked “Please read”. She looked over, they waved shyly, they all smiled and nodded. That was it.

Today, we had feared missing each other, as our arrangements faltered, and I had imagined a proto-diva furious at being kept waiting. “Gosh,” she says, blinking widely at the idea. “I’m not terribly good at being furious.” Unlike, say, Kate Winslet or Billie Piper, there is no stark mismatch between Morahan in mufti and her period-piece persona. She carries something of her roles within her at all times – an actress for all eras, one with a taste for the tricky and opaque.

“I like parts where, on first reading, I have no idea how I will play the character; where things aren’t obvious, where you need to work it out.”

Her new one ticks all the boxes: she plays Clair in Martin Crimp’s new play, The City, at the Royal Court in London.

She’s a translator whose marriage to Chris (Benedict Cum-berbatch) is in trouble. The piece explores “secrets, relationships, how ugly human beings can be when they are backed into a corner”. Actually, she struggles to say exactly what it is about, not because she lacks clarity, but because the drama verges on surreal at times, and because she is still worrying at it. Its director is the controversial Katie Mitchell, a friend and mentor – this is their third collaboration – whose painstaking approach to unravelling every aspect of character has become Morahan’s method. “Nothing is left to chance: it gives me something to fall back on, especially since I didn’t train. It’s about being absolutely specific.”

Hattie Morahan is the younger daughter of the actress Anna Carteret and the television and theatre director Chris-topher Morahan, 78 and still working. She was five when he directed The Jewel in the Crown. “For a long time, I thought India was near Manchester,” she laughs, “because my dad was working for Granada but he kept going to India.” Her first job, at 16, was for her father, when she was recruited to play the lead in The Peacock Spring (1996), a Rumer Godden story shot in India, with Peter Egan and Madhur Jaffrey. Her character, a troubled English girl, has an affair with an Indian poet – “I had to kiss Naveen Andrews,” she giggles at the memory. “He’s in Lost now.” Her father insisted she audition, but you get the impression that the part, and the ensuing career, was hers for the snatching, as long as she could prove her worth. “It was an astonishing experience, but when you’re 16, you just think, ‘This is nice, this is what acting’s like.’ ” Besides, her childhood had prepared her.

As a schoolgirl, she attended Laurence Olivier’s summer parties, and on one occasion was chivvied by her parents to go inside and finish her homework; eventually, her elderly host wheeled himself into the sitting room and helped her with it. “I just thought, ‘Oh, that’s nice of him,’ ” she laughs. “It seems so silly now, Lord Olivier helping me with my maths or whatever. In my childhood, though, it was all normalised.”

She was privately schooled in London and rural Surrey, a bookish and extrovert child by turns, a mimic and a tomboy. She visited sets and theatres; she watched her mother act in Shaw and Shakespeare; she saw her Polina in Peter Hall’s 1997 production of The Seagull with Felicity Kendal and Dominic West “several times”. After her GCSEs, she accompanied Carteret to Broadway for a run of An Ideal Husband – but their lives weren’t public property: no celebrity, no paparazzi, just cultured professionals whose job happened to be acting, the way she would like to manage her own affairs if she gets the chance. “Why would anyone care what I wear or where I go on holiday?” she guffaws. “If I get anything from my parents, it’s that the work matters. They are both passionate and serious about what they do. They never let me see this business as an easy option.”

It was not her parents, but a 1994 Hamlet in the West End, with Stephen Dillane as the prince, that really inspired the teenager to act. “It was acting of such truthfulness, as if he wasn’t on stage but in the same room, just talking to you.” When she told her parents of her decision, it was as if she had sensibly decided to join the family firm. You could never say about Morahan that she has had it hard, and maybe that’s why she chases difficulty the way her peers pursue the big money.

She has no interest in carving a lucrative niche for herself. She wouldn’t undertake a character similar to Elinor or any other recent creation; she craves new, enigmatic, unexpected challenges when, paradoxically, the theatre could easily be a comfort zone for her, a home-from-home in which everyone she meets on jobs sends their love to her parents and tells her they remember her in her pram. “I don’t resent that,” she says benignly, though you can see it could be infuriating. When her parents are in the audience, she is nervous. “It’s great when they come. We give each other notes.” Of course, she is far too polite and careful a creature to say anything else, but I wonder if she wouldn’t prefer them to be simply thrilled with her rather than helpful and – dread word – “constructive”?

Their daughter is like them, however: clever, thoughtful, analytical. She read English at Cambridge, where most of her time was spent acting. “In my first weekend there, I auditioned for 11 plays in one day.” Her parents advised drama school, but she was too itchy to get going and made a deal with them: if she wasn’t working a year after leaving university, she would go off and learn her craft. In fact, she was offered a contract by the Royal Shakespeare Company, where the technical classes, voice coaching and sense of belonging provided much of what she would have learnt in three years at Rada. She acted in a new David Edgar play, The Prisoner’s Dilemma, understudied Ophelia and was cast as Gentlewoman to Sam West’s Hamlet.

Morahan has been singled out as one to watch. She was much praised for her doomed, vulnerable 15-year-old Iphigenia (the actress was a decade older) in Mitchell’s 2004 Iphigenia at Aulis at the National, for which she talked to teenage girls on buses “for weeks”. Then, in 2006, in Mitchell’s radical, grimly designed The Seagull, again at the National – condemned as “bird-brained” by outraged critics – Morahan’s Nina garnered an Ian Charleson award. She is also unusual in her devotion to classical theatre, which has little to do with ambition. While she enjoyed the primetime BBC slot that raised her profile, you can tell she has never dreamt of making her fortune in film-making, which she finds “bitty” and transient – though she was beguiled by the extravagance of The Golden Compass, in which she played Sister Clara (“I had my own dog as my daemon”), compared to the draughty dressing rooms and compromises of the pioneering theatre she sees as the real point. “I’ve always seen myself as a classical actor. The film world looks fun, but what I aspired to was playing Juliet or Nora. That’s what I still aspire to.” Besides, Morahan’s undoubted beauty is not standard-issue perfection, for which she seems almost thankful. “You want an actor to look like they’ve lived. Your face is your tool box. For me, acting is portraying humanity in all its flawed messiness.”

In preparing Sense and Sensibility, she avoided the Ang Lee film: comparing herself to Emma Thompson, who starred, wrote the screenplay and won the Oscar, would have been too daunting, she says, but I’m not sure I believe her. “Shakespeare is done all the time,” she shrugs, when I ask if the BBC version wasn’t too soon. “When I did The Seagull, there were three productions that year, but what you bring to the character is original by virtue of the fact that it’s you.”

What Morahan used was her youth, undercutting what Jane Austen describes as Elinor’s “coolness of judgment” with the inevitable uncertainties of her age. “I thought, ‘Well, okay, we’ve got a chance to do it differently. I’m not 19, but we could appear to be young girls, so the story is slightly different, one of first love.’ Elinor has maturity beyond her years, but it’s not tested, so she thinks she can cope more than she can. There’s a point where Marianne is seriously ill, she’s on her own at Cleveland, her mother’s not there and she suddenly feels about 10 years old.”

There is a toughness about Morahan, for all her graciousness, maybe a touch of old empire spirit (her mother was born in India, her father is clearly drawn to the subcontinent), a mixture of delicacy and the sleeves-rolled-up trouper who is raised never to whinge or forget how lucky she is. Her fiancé is the actor and director Blake Ritson (Edmund Bertram in last year’s ITV Mansfield Park), who has made three short films with his brother. In the latest, Good Boy, his fiancée appears alongside Jessica Hynes and Joanna Page, but was also the costume designer; on his previous movies, she was script supervisor. “He needs help behind the scenes. I’m happy to supply it. I just like to get on with it.”

Before we started talking, we had ordered an avocado salad, the main ingredient of which was bullet-hard. “Don’t eat it,” I had cautioned her, but the unflinching actress just smiled. As we say goodbye, I notice that while my plate is scattered with pale green rocks, hers is empty.

The City previews at the Royal Court, SW1, from April 24

Editor's choice

• Burning Bush with W
• Revolution at the new Saatchi Gallery
• Boy George on sex, drugs and Amy Winehouse