There's a lovely moment in BBC3's new drama, Being Human, where Andrea Riseborough explains that she's not as other women. "I'm something else... a ghost," she tells her flatmate's girlfriend. Seeing the look of incomprehension on the girl's face, she adds, with wry, Northern wit: "I'm not a fan of the word."
With her heavy-lidded blue eyes and chalk-white complexion, there is an otherworldly quality to Riseborough. She is 26, but looks, as she puts it, "about 12", and spent much of her time at Rada playing virgins. But Riseborough – who grew up in working-class Newcastle and has a soft Geordie accent – is also a terrific character actress. She can do classical theatre and mainstream TV; she can do femme fatale and street urchin. And very often she's completely unrecognisable.
Last year she played a Croatian-Serb beautician (all leather trousers and politically incorrect views) in the Royal Court's coruscating The Pain and the Itch; a New Labour intern in BBC2's Party Animals; and the love interest in the Mitchell and Webb film Magicians.
She was also cast as the young Margaret Thatcher in The Long Walk to Finchley, a BBC2 drama that will go out later in the year. No wonder everyone is queuing up to work with her, from Sir Peter Hall and Mike Leigh to the artist Sam Taylor-Wood.
Riseborough is very proud of Being Human, a one-off 60-minute drama that has the glossy production values of Torchwood and Spooks. Three twentysomething misfits – a werewolf, a vampire and a ghost – are thrown together by their dark secrets and set up house together.
Riseborough's character, Annie, died in a tragic accident and can't move on. Dressed in sweatpants and slippers, making endless cups of tea, she is the antithesis of the tragic Victorian spirit. "She's just a really, really sweet ghost-next-door," says Riseborough. "I decided she might be from Barnsley, she might have done a degree in psychology at Loughborough – before the accident she was engaged and happy, her whole life ahead of her. For a long time she doesn't realise she's dead. She's ballsy but vulnerable."
Written by the playwright Toby Whithouse (who has also penned episodes of Torchwood, Doctor Who and Hotel Babylon), Being Human is full of black humour, but also subtly political. "Toby Whithouse writes for Martin Freeman," says Riseborough, "and so it has that feel of The Office, but there's also a deeper meaning."
It's clearly fantasy, but it tackles loneliness, rejection and fear of sexuality. We feel genuine sympathy for George (Russell Tovey from The History Boys), who transforms into a werewolf every full moon, while vampire Mitchell (Guy Flanagan) is a loner doomed to ruin every relationship.
You could argue that each character's affliction is a metaphor for the difficulties of adolescence. As Riseborough sees it: "It's all about being 'other'. The vampire could be a smack addict, the werewolf someone who has contracted a horrible disease, the ghost an agoraphobic. Did you know that agoraphobia is fear of the market place? Agora means market place in Greek."
It's a typically thoughtful observation. Although she decided against university and left school at 17 – "I perhaps lost a Thesaurus through it and a couple of Tolstoy novels," she jokes – Riseborough is a demon researcher. She spent time in Croatia before playing her character in The Pain and the Itch, and read everything she could get her hands on about Thatcher. After school she spent three years waitressing, made short films, choreographed contemporary dance, started a greetings card company and began to learn rudimentary Cantonese.
No wonder she knows more about real life than many drama school graduates. She is touchingly positive about everyone she works with, but you sense an inner steel. Her father was a car dealer, her mother a secretary. A bookish child, she spent time writing, painting and drawing in her bedroom. When Riseborough was nine, her drama teacher recommended her for an audition at the People's Theatre (home of the RSC in Newcastle), and soon she was making her stage debut. She later joined the National Youth Theatre and won the 1999 Mike Figgis Award for her performance in Dog Days.
But, even when she won a place at Rada, she had to fight to avoid being stereotyped. "I remember at one point thinking: 'not another virgin, please, no.' And then I realised a way to break out of that: every virgin's different. We were all virgins once. So provided you make choices and create an entire person, your virgin might grow up in Florence or have a seriously bad relationship with her father. And I think my tutors realised I could be far more malleable as an actor." By the third year she had a top agent.
After Rada she was cast in A Brief History of Helen of Troy at the Soho Theatre, and nominated as Best Newcomer at the 2005 Theatregoers' Choice Awards. Next came a six-month stint at the National, playing in a trilogy of plays about young people, Burn, Chatroom and Citizenship.
Hall then offered her two more killer virgins – the lead role in Miss Julie, and Isabella in Measure for Measure, which won her the 2006 Ian Charleson Award.
But you'll probably know her best from TV as the splendidly pushy Kirsty in Party Animals. She loved the fact that Kirsty's sexual bravado was born of loneliness and insecurity – but that finally her character began to develop a political conscience. And now she's playing another political animal. Riseborough's own politics couldn't be further from Thatcher's, but, filming The Long Walk to Finchley, she came to admire the Iron Lady. "That's my job, to be empathic, to be more than sympathetic. But I, as Andrea, did end up feeling great admiration for her struggle, for what she achieved – whether I agree with what she achieved or not."
The film covers Thatcher's early life, from her mid-twenties when she fought doggedly to be selected as a Conservative candidate, to the age of 34 when she became MP for Finchley. We won't get the full comedy Thatch persona in bouffant blond wig. Instead, Riseborough plays her as a slight, dark-haired woman. "We wanted Maggie to be unrecognisable at the beginning, so she's a young girl with an RP accent from Grantham, and then I gradually develop into her."
The transformation is achieved with very little make-up, but Riseborough is a master of body language: "Maggie just knew she was right about everything, and she ended up craning her neck so bloody far forward that her handbag was leading her around up and down the street! Her little tiny frame just couldn't contain this drive."
Right now, she's in the middle of rehearsals for the Soho Theatre's A Couple of Poor, Polish-Speaking Romanians. Written by Dorota Maslowska, it's billed as a fast-paced road trip of the mind. Gina, Riseborough's character, and her fellow traveller are violent and amoral. They might be gangsters or they might just be soap opera actors on a weekend bender. We're never quite sure. But this is a generation that has been betrayed by consumer capitalism. "Gina's a child really, a child with a child. I'm playing her boyish and unavoidably rough."
She's not allowed to talk about her role in Leigh's next film, Happy-Go-Lucky, except to say that it was an extraordinary working experience. But words come pouring out about filming Taylor-Wood's short film Love You More. "Sam is such an uncompromising artist but she allows everyone else space to be their own artist. It was a godsend of a piece artistically, because we had Seamus McGarvey shooting it, who always does everything with Sam and shot Atonement. We had Patrick Marber as the writer and Anthony Minghella's company producing it."
The film is set in the summer of 1978 – "although we filmed in winter so we had to suck ice cubes before the shoot so we didn't have cold breath." Riseborough plays a 15-year-old punk brought together with a schoolboy (Harry Treadaway) on the day The Buzzcocks release the single of the title. "On set we really felt we were those kids falling in love when everything was exciting and new and crazy."
As for being hailed as one of the hot new faces of 2008, Riseborough remains level-headed. "I think: 'Don't be silly, stop thinking about it.' It's the greatest honour to do a job you love. Some days I wake up feeling shattered but mostly I'm ecstatic about what I do.'
'Being Human' starts at 9pm on 18 February on BBC3; 'A Couple of Poor, Polish-Speaking Romanians' opens at the Soho Theatre, London W1 (0870 429 6883) on 28 FebruaryReuse content