Karen Gillan: just what the doctor ordered

Red alert! It's Karen Gillan: the giant flame-haired time-travelling Scotswoman with whom the British nation has fallen madly, hopelessly and devotedly in love. Here she comes, fresh from these photographs, pounding down the thickly carpeted stairs of Fulham Palace in a dirty great pair of heels and a shimmering fairy-tale frock, all six foot of her and, I can't help noticing, most of it leg.

If you've watched the last few weeks of Doctor Who you'll have seen her alter ego, Amy Pond, skitter down frowsty spaceship corridors, across sinister English village greens, around vampire-filled Venetian palazzi and through a forest populated by malignant alien gargoyles. 'The other day I was looking at a version of myself in a new computer game and I asked for the legs to be changed.' They were too muscular, 'almost like a body-builder's', and she asked for them to be made more feminine. See, she's noticed, too.

As we find a space in the palace café to drink tea, it quickly becomes clear that Karen is much more comfortable talking about sex than politics. I ask if she voted in the General Election. 'That's a secret!' she exclaims in the same excitable Scottish tones she uses on TV. 'Isn't it? I don't talk about that sort of stuff.' If Karen thinks that the former Doctor Who, David Tennant, was right to come out for Gordon Brown, and agrees with her boss, Steven Moffat, the programme's new head writer, that the country should be run by anyone but the Tories, then the truth can't yet be told. Being the Doctor's sidekick is clearly more of a diplomatic role than it used to be.

Get her on the precise nature of the relationship between Amy and Matt Smith's freshly regenerated Doctor, however, and some Newsnight-standard comment and analysis gush forth. First we talk about the peculiar but oddly compelling shape of her co-star's head. 'I've never seen anything like it,' she agrees. 'And he has an aura as well. A head and an aura.' Smith is, apparently, as eccentric as he seems. 'He has some strange mannerisms but he really doesn't see it. All those odd things he does with his hands.' She performs an explanatory mime that suggests she may one day find work with outré director Lars von Trier. 'As you spend more time with Matt you don't notice it so much and he becomes normal. And that's how it must be for him. He feels normal. But he isn't. Which is great for the Doctor.'

And for her, too, it seems. 'Sometimes they're like brother and sister, getting at each other and winding each other up. But Amy is also attracted to the Doctor. It's just that
she's not attracted to him in a romantic way. That's what separates her from the other companions who came before. She's not secretly in love with the Doctor. She wants something else.'

This is the attitude she played out in a scene that caused a mid-size media kerfuffle a couple of weeks ago. Amy recumbent on the duvet and making mildly smutty remarks about being 'sorted out'. Amy grabbing the Doctor by the braces and planting an enormous wet smacker on his great big bony face. Amy telling the Doctor that she didn't care if she was getting married in the morning, as she wasn't looking for anything long-term. How, I wonder, do you recover from a one-night stand with a Time Lord? 'Amy would take that in her stride,' says Karen. 'In the morning she would probably have been back to being his sister.'

Modern, isn't she? A bit too modern for Mediawatch-UK, the current form of Mary Whitehouse's protest outfit, which spent the 1970s attacking Doctor Who for being too violent. It has now suggested that the programme was bringing a new and unwelcome note of sex to Saturday teatime. Does Karen think they have a point? 'I read the complaints, but I don't see that it's very bad at all. The Doctor isn't reciprocating, so it's not inappropriate. We're not sending out bad messages.'

Karen was born in Inverness in 1987, when Bonnie Langford was in the Tardis and nobody was worrying about whether the companion was getting too fresh with Sylvester McCoy's Doctor. Not even Karen's mother Marie, a committed user of Dalek bubble bath long before her daughter gave her the excuse. The less excitable John Gillan, who manages a care home in Kinmylies, claims that the infant Karen would point at the television and announce her intention to be on it. Karen is sceptical but does concede that she was a starstruck teenager.

She left home at 16 to study performance at Telford College, Edinburgh, then followed in Bonnie Langford's spangled footsteps to the Italia Conti drama school near the Barbican. From there she started to get smallish roles on TV: a few lines in an episode of the detective show Rebus, a turn as a soothsayer in a David Tennant episode of Doctor Who, and spots as a comedy headmistress and a lesbian bride in The Kevin Bishop Show (no, me neither). Then the work dried up and the pint-pulling began. She spent a year behind the bar of The Pilgrim pub in Kennington, wondering if she'd done the right thing to launch herself into an acting career without formulating any kind of Plan B. It was brought to an end by a talent-spotter from a modelling agency, who noticed that Karen didn't have to stretch very far to reach the optics and asked if she fancied parading on the runway in the Allegra Hicks show at London Fashion Week 2007. 'It was depressing not working for so long,' she reflects. 'I hated not being involved in acting, but looking back on it I'm pleased it happened. Otherwise I wouldn't know what it's like to have a normal job.'

She secured her abnormal job a year ago, after a clandestine audition in which the applicants passed BBC reception only by uttering the codewords 'panic moon', an anagram for 'companion'. Once she'd said yes – or, to be more accurate, screamed it down the phone – her new employers sat her down and gave her an interview in which the new recruit was invited to volunteer anything from her past that might conceivably cause work for the press officers. 'Surreal' is how she describes the experience, though, naturally, she won't divulge any details. 'It makes you realise how serious it all is. But it's only a moment. It's not hanging over you all the time.'

Other things are, however. Such as the paparazzi, who were there to snap her on a Welsh beach during her first day of filming, and to clock her hanging out at a garden centre in Suffolk where she was looking at bonsai trees with her boyfriend, a 24-year-old photographer called Patrick Green. The fruit of that expedition is sitting on her windowsill. 'A succulent. Alberta Graptoveria. I called it Albert. Just to clarify, I don't really know anything about bonsai trees.'

The Doctor Who schedule, too, seems pretty overpowering: nine months of 11-day work stints with one day off between each block. There are good biological reasons why, during her first season on the programme, Billie Piper developed a spot so gigantic and tenacious that the production team gave it a nickname. 'We work such long hours that it completely dominates your life,' says Karen. 'I had a few days off once and I didn't like it when I came back because I felt out of touch. I was out of it for two days and I felt I'd lost Amy.' And possessing Amy is clearly a source of strength and pleasure for Gillan. 'She's a lot cooler than me,' she says. 'She has a different walk from me. She struts. She's bad.'

She'll stay with the series beyond this year: whatever tests June's season finale has in store for Amy, her survival is assured. 'It saddens me to think of the day when it'll all be over,' she admits. 'But once you're in Doctor Who you're in it forever.' Longer than that, sometimes. In December 1998, the crematorium curtains closed on the coffin of Michael Craze, 56, one of Patrick Troughton's sidekicks, to the ominous diddly-dum-diddly-dum of the theme tune. Other actors have had extreme experiences in their post-Tardis years. Anneke Wills, another Troughton co-star, disappeared into the ashram of the Bhagwan Shree Rajneesh. As for Katy Manning, who tussled with giant maggots alongside Jon Pertwee