Jodhi May swaggers slowly across the room in a tight yellow minidress. She stops by the bed, her voluptuous breasts practically spilling into the transfixed teenage face sitting before her. “Why don't you make a move?” she says, grinding up against the young male, a meek adolescent virgin, half her age. “You can touch if you like.” Some moments later, she's stripping him down. “You are very, very naughty,” she purrs. And moments later, she's on top, straddling him, promising him that he won't be sorry, and offering him the untold riches of sexual pleasure in extremis.

This, it is safe to say, is not your typical Jodhi May performance. As Evelyn Adams, the lascivious smalltown mother who seduces local schoolboy Joe (Harry Eden) in Flashbacks of a Fool, the 32-year-old Londoner has put a world of hip-smacking crackle between her and her past screen turns. This is not the Jodhi May - cosseted in costumes and reeking of reserve - of Daniel Deronda, The Mayor of Casterbridge or The House of Mirth. Instead, she agrees, it's something entirely different. “I'd never done anything like it before,” she says, sitting giddily in a London members' bar. “In fact, when I went in to do some post-synching on the dialogue, four months after the shoot, I saw a bit of myself in the bedroom seduction scene, and I said, ‘Who the f*** is that?! She is absolutely terrifying!'”

The film, as the title indicates, is mostly a flashback in the mind of the drug-addled alcoholic superstar actor Joe Scott (played by Daniel Craig, also the film's producer, in something of a cheeky image tweak). Thus the childhood scenes, set in an unnamed English seaside village, though filmed in sunny South Africa, all revolve around Evelyn's aggressive seduction of the young Joe, and how that ultimately defines the tortured adult he will later become. It's a show-stopper of a performance from May, a fascinating amalgam of broad Carry On come-ons, genuine corpulent va-va-voom, and an underlying sense of tragic desperation.

Today, in grey T-shirt and black denims, she has thankfully stowed Evelyn's sexual energy. And yet the role, it seems, has left a certain liberated twinkle in her eye. “I think the point is that Evelyn's supposed to be potently sexual, terrifying and utterly desirable at the same time,” she says. “She is absolutely a woman and there is something overwhelming about her seduction. It's a very disturbing thing, and I think it should be.”

She adds that Evelyn's been good for her in many ways. Professionally, she's just finished another movie with Craig, a Second World War blockbuster directed by Ed Zwick (Blood Diamond) called Defiance. Plus, she's played Rembrandt's mistress in Nightwatching, and Einstein's wife Elsa in Einstein and Eddington. Personally, too, she seems at ease with herself, and has none of the wary brain-box introspection that has defined so many of her previous press encounters - in one, she famously revealed nothing about herself, other than to announce sombrely, “I find stoicism fascinating.”

That, of course, was the May of old. Raised in Islington, North London, by her French mother, an art teacher (separated from May's German father), she was plucked from obscurity when the casting guru Susie Figgis came calling at the Camden School for Girls. Her first role, as the ostracised daughter of an anti-apartheid activist in A World Apart (1988), earned her a best actress award, aged 12, at the Cannes Film Festival (she remains its youngest recipient). Yet the job of acting was never allowed to take precedence over school work.

A place at Oxford followed, although she is, adamantly, not one of the Oxbridge elite. At university she performed only during holidays, filming period dramas such as The Woodlanders and The Gambler. She soon became known for her exquisite turns in period roles, often bringing unexpected gravitas to supporting characters, such as the victimised Mirah Lapidoth in Daniel Deronda, or the scheming socialite Grace Stepney in The House of Mirth.

And yet the familiarity of this period milieu seemed to breed contempt, creating in May a persona who was, perhaps, unduly serious about her craft and unfortunately locked into an ever-replenishing cycle of costume- dramas. I ask her why it took her so long to choose an edgy, aggressive role such as Evelyn in Flashbacks of a Fool. “That's a bloody good question,” she says, before explaining the reality of type-casting. “People really expect you to do what you've done before,” she says. “They associate you with a certain type of role and are not necessarily able to think of you outside of that context.” Thankfully, she says, every time she met Baillie Walsh, the director of Flashbacks, she was completely in character, and in costume. “I wore the f***ing high heels, and he was at the other end of the room going, ‘Ahhhh!'” she jokes.

Right now, this newly liberated May is open about her future. She speaks enthusiastically about her time on Zwick's Defiance, and about her faith in the creative aspects of Hollywood. When I ask if she's planning a feature debut she beams broadly and says, “Maybe.” What's it about? “I'm not telling you. If you talk about these things, sometimes they don't happen.”

Instead, and in the spirit of liberation, we gaily wade into her private life. Does she have a boyfriend? “Yes,” she says, grinning coyly. What does he do? “He's not in the arts,” she says, still grinning but giving me a ‘that's as much as you're getting' stare. I ask her some stupid questions. How did it feel, re Daniel Craig, to practically rape a young James Bond? “Oh my God!” she howls, “It wasn't rape!” Would she take $20 million to star in Live Free or Die Even Harder? “God, I don't know - life's too short to worry about money.” And, crucially, finally, when she wakes up in the morning, is she an actress or a real person? “I honestly don't know,” she says. “I know it's a cliché to say this, but acting is an addiction for me. It's just something that I have to do.”

Flashbacks of a Fool is released on April 18

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