Six years after last joining forces with Fox Mulder in The X-files, agent Dana Scully is back. And Esquire is more than happy to see her return.

Whatever the stars say, it is possible to make a decision when it comes to fame: the kind of attention a person gets is as much down to them as it is to the men with the long lenses, and Gillian Anderson is the living proof of it. We meet for lunch in a loud restaurant in a London market, and from our table, I watch her arrival. She comes in a cab, and when she gets out, delicately stepping over a yellowing cabbage leaf as she does, no one gives her so much as a second glace. Why? Because she isn’t making a fuss. No baseball cap, no sunglasses, no beefy giant to open car doors. Later, when she is ready to leave, I ask if I should ring for a taxi, so she won’t have to stand on the street in the rain. “Oh, I’ll be fine,” She says mildly. And off she goes. I watch her all the way to the corner, and she is fine. Wedge espardrilles, leather coat, high, tight ponytail, little or no make-up. She could be almost anyone, really. Until you remember that, around the world, a million sci-fi nerds still have her face as their screen saver.

A few other Anderson observations, she eats. She orders two courses, one of which is a bit of beef so thick it might have come straight out of the pages of the Dandy and she finishes them. She drinks coffee, not herbal tea. When you ask her personal questions, she doesn’t freak out, and she asks you stuff, too. She is… polite, interested. I can’t tell you how unusual all this is. When, afterwards, I told a friend how nice she was, he said: “But she’s an actor. She was probably just acting nice.” But that’s the thing. A lot of Hollywood women – most of the ones I’ve met – don’t bother to play nice. They pick at their salad, and look sulky, and will only talk about the work. Which leads me to conclude – in spite of the old X-Files tag line that read “Deceive, Inveigle, Obfuscate” – that those who play nice might actually be nice. In the end, when Anderson and I are talking about how mean Hollywood can be to older women (for older, read anything over 35; and no, she has not had her face done – it comes with a number of very charming wrinkles), I blurt this out: Hollywood is full of weirdos! “Well, I saw Gwyneth on Jonathan Ross,” she says, “And she seemed to be lovely and normal. Am I wrong?” She sounds like butter wouldn’t melt in her mouth, but something about the cast of her eyes makes me think that she knows exactly what I mean.

Anderson is limbering up for the onslaught that is the launch of the second X-Files movie, The X-Files: I Want To Believe (out on 1 August). Only it’s tricky for us to talk about it much because its plot is so swathed in secrecy that not even Anderson herself has seen it the whole way through. “My working script only had the bits with me in it.” But how does she feel about the film in terms of how it will impact on her? It is 10 years since the last X-files film, and six years since the TV series on which it was based ended, since then, she has put an awful lot of energy into trying to put what she called “some distance” between her and FBI agent Dana Scully, the role that made her famous. She did this with a series of unexpected roles, among them Lady Dedlock in the BBC’s Bleak House, for which she was nominated for a corset-full of awards, and a Northern Irish council house mother in a film about greyhounds, The Mighty Celt. Why would she go back to The X-files? “It was the right time,” she says, “There was enough distance.” Her fantasy, she says, is that Scully and the rest of her life are now so separate that reprising the role doesn’t really matter. But perhaps, she adds, that really is only a fantasy. “What impact is it going to have? Is it going to make people forget I can do anything other than Scully? Or is it going to raise my profile for a little bit, so it’s more difficult for me to walk around town, but then just die down? Or is it going to have a positive effect, and maybe someone in America will pay attention and say: so she can act. It’s so hard to know.” And if it’s the latter, and the roles pour in, the question is: will she be ready? “Doing it was so exhausting. Partly because I’m nearly 40, partly because I’m pregnant (She is expecting her third child in the autumn) and had morning sickness. Maybe I’m not in as good shape as I could be. Maybe I’m just a wimp. David (Duchovny, aka Fox Mulder) is in a lot better shape. In the film, David does a lot of running about, and I do a lot of walking down corridors.”

Does she really feel that Hollywood has forgotten her? “Well, the decision that I made to come here was a big decision, made to the consternation of people who have some stake in my career. You really do need to be there. If you’re not, people do say: what is she up to? I forget that films like The Mighty Celt and Straightheads did not see the light of day out there. After The Last King of Scotland even though my role was only tiny, all of a sudden I was on different lists. I’d get calls: you’re on a shortlist!” But she doesn’t regret the move. “No. I don’t regret anything at all. But I have hired a publicist in the last couple of weeks, something that I’ve never done before. I’m entering a different time, a more challenging period. There are so many great actresses of a similar age, and a real lack of parts. I worry, but it’s more that I feel: what a shame, I’ve so much yet to give. I feel like I have only just begun.”

She came to London in 2002, a move that felt natural to her, however unlikely it may have looked to outsiders. Anderson, who has a cut-glass English accent with twangy top notes of LA, grew up in the city, in Crouch End, only leaving it when she was 11, and her father, who’d been attending film school, took his family back to America. She loves it both for its own sake – “I think it’s more beautiful than Paris” – but also because of the relative anonymity is provides; according to her, the paparazzi are not half so demented here as in LA.

The same year, she met Julian Ozanne, a journalist turned bio-fuel entrepreneur, and having thought he was obnoxious at first, finally married him. I interviewed her three years ago, just eight months after their wedding on Shella Island, off the coast of Kenya. She had nothing but good things to say about him then, but there was also something distracted about her, as though, somewhere in her head, she was listening to a fly bash against a window. She complained that she sometimes wore herself out with her own seriousness, and confessed that her natural tendency in life was destructive. “I would never really claim sanity,” she said, “But I put on a good front.” With hindsight, one puts this sense of preoccupation down to the fact that she was perhaps not quite so content as she pretended to be. The marriage to Ozanne lasted just 16 months, and only three months after their separation it was revealed that she and her new partner, Mark Griffiths, who runs a car-clamping business, were expecting a baby (Oscar is now 19 months old). “There is a buoyancy,” she says, when I remark on the fact that she seems more obvious happy now. “I can’t say I’m that way all the time, but I feel things are kind of good. My daughter (Piper, 13, by her first husband, Clyde Klotz), and my son, and my relationship with my partner is good and solid.”

What is Griffiths like? All I know about him is that he was once “linked” to Geri Halliwell. “He’s absolutely reliable. He’s willing to do whatever it takes to make this family work. He’s taken on a stepdaughter, which isn’t necessarily rewarding at times, or not for a lot of step-parents, and he’s handled it very well. He shows up for everything: the difficult stuff, and the fun stuff. He’s wiling to take responsibility.”

Will she marry again? “I don’t know, I can actually say the words ‘my second husband and that is so weird. I don’t feel like I’m old enough. And it didn’t work twice (she married and divorced Klotz, a production designer on The X-Files, when she was in her twenties), so is marriage in and of itself part of my downfall? I liked the feeling initially. It felt wonderful and solid and wholesome. But you can only live for the moment and, based on the information that you have, do your best.”

So, to sum up, she’s not exactly keen to say the words: my third husband. That’s part of it. But it (her relationship with Griffiths) works really well as it is.” What if he proposed? “ I think I’ve made it clear enough that he wouldn’t, necessarily. But it’s possible, at some point, that I’ll be OK with it, and then it might be me who ends up going down on one knee.”

That Anderson had a fairly difficult adolescence is well known. She has never shied away from talking about it. First, there was the move to Michigan from London. Then, having been an only child for so long, two younger siblings suddenly appeared. Anderson responded by gluing shut the door of her high school and becoming a punk, complete with highly unsuitable boyfriends. It must, therefore, have struck her that she has now, however unintentionally, put her daughter, Piper, through the same stuff: first the move from Vancouver, where Piper was living with her father, then the arrival of a baby brother. “I know,” she says, “It’s very odd. What’s strange is that it’s almost like I’m observing it from the outside. But it’s not at any stretch; well, my mum did this. None of it is planned. But it is an opportunity for me to do things differently. She appreciates London, but she wasn’t so crazy about the idea (of a baby) to begin with. She is quite a tomboy, and when she was in Canada, and I was sharing custody, whenever I saw her, it was very much the two of us. Then all of a sudden: new relationship, new baby. There was a lot of fear around it. But, instead of losing something, what’s happened is that she’s ended up with this adorable little boy who adores her.” Anderson then proceeds to give me a short but heartfelt lecture – including baby pictures, stored on her mobile phone – about how very important it is that I breed.

She is, she tells me, trying hard not to put on too much weight; last time she was pregnant she put on 50 pounds, and half as much again with Piper (she lost it, not with some Madonna-style super regime – “I went running twice in 16 months,” she says sardonically – but first by “waiting” to see what her body did of its own accord, and then, when things got really desperate, by cutting out wheat and sugar).

She needs to stay on top of the whole body situation because a lot will be going on. First, the days spent locked in a Los Angeles hotel room talking about alien life forms – or whatever; your guess is as good as mine – for The X-Files, then the release of two other films: How To Lose Friends & Alienate People, a comedy based on Toby Young’s book of the same name starring Simon Pegg, and Boogie Woogie, an art world satire, with Alan Cumming. Then, early next year, she will take to the stage at Donmar Warehouse to play Nora in Ibsen’s A Doll’s House. “I see her as bird-like, so… you know, with Oscar, it had been a few years since I had allowed myself to let go, so it was like, “Woo-hoo!” She winces, though I note gratefully that the thought isn’t quite scary enough to put her off her beef and horseradish.