Her career may seem endless, but Gillian Anderson isn't taking anything for granted. Here, she muses on ageing, sexism and her current co-star, a certain Jamie 'Fifty Shades' Dornan.

Gillian Anderson's six-year-old son Felix recently walked into a room in their Wiltshire home carrying a box-set of The X-Files he had found. 'He pointed at it and said, "Is that you?" and I said, "Yeah", 'Anderson recalls. 'He was like, "Oh" and put it back in the drawer.'
She laughs, delighted by the fact her son could be so unimpressed by the television phenomenon that made hers mother a star in the 199os.
These days, Anderson, 46, is no longer defined by her nine-year stint as special agent Dana Scully on the sci-fi series. Since her glorious turn as DSl Stella Gibson in the BBC's hit crime drama The Fall last year, Anderson has won over a whole new fanbase. Of course, it doesn't hurt that her co-star in the Belfast-set detective series is the Northern Irish actor Jamie Dornan, 32, whose ludicrous good looks had many female viewers debating how appropriate it really was to fancy a cold-blooded misogynist serial killer. The much-anticipated second season is about to air and, Anderson promises, 'It's even better than the first.'
Sat in the tea room of the Hotel Café Royal in London's Piccadilly, the décor boasts so much gold leaf it feels like being inside a box of Ferrero Rocher. The gilded hue of the mirror frames and furniture matches Anderson's blonde tresses almost exactly. She looks absurdly fresh-faced and bright-eyed for someone who has flown in from Belfast a few hours previously, having just wrapped filming on the second series. For most of the afternoon, and throughout our cover shoot, she has been trailing a wheeled suitcase behind her, refusing all offers of help.

The first series of The Fall was one of Dornan's first serious acting jobs, prior to which he was best known for his (often semi-naked) modelling. Since then, of course, everything has changed for him. In February, he will star as Christian Grey in Sam Taylor-Johnson's eagerly anticipated film adaptation of Fifty Shades Of Grey.
'I've been surprised at how funny he is,' says Anderson, in the way that being funny and as ridiculously good-looking as Dornan is indeed pleasantly surprising. 'He's very, very funny and good at telling stories. He's a good mimic as well.' Then, suddenly sounding quite motherly, she adds, 'He's a lovely young lad. On the first series, people were like, "Who is this guy? Is he an ex-model or something?" Now people don't ever want to talk to me about The X-Files. They only want to ask about Jamie Dornan.'

Of course, Anderson has plenty of other things to talk about. Professionally and personally, she is a woman with a very rich history. An actress who resolutely refuses to be typecast, she dances from silver screen (The Last King Of Scotland) to stage (most recently Blanche DuBois in A the Young Vic's production of A Streetcar Named Desire).
And, of course, the medium in which she has most made her mark, television, where she has gone from corset (Bleak House, Great Expectations) to cannibalism (Hannibal) with ease - and critical acclaim.
Despite this impressive CV, Anderson readily admits The Fall's Stella is the role of a lifetime. The fictional detective has become the poster child for a new kind of feminist hero: a no-nonsense woman in a man's world, equipped with intelligence, gravitas and an excellent wardrobe of silk blouses. Unlike Prime Suspect's DCI Jane Tenninson (played by Helen Mirren in the 1990s), who adopted a masculine approach to be taken seriously by her colleagues, Gibson embraces her sexuality and refuses to apologise for it.
Are there similarities between Anderson and her detective alter ego? 'She's not a small-talker and I'm actually not either, as a rule,' Anderson replies in a well-enunciated English accent. She has lived here for several years, splitting her time between north London and Wiltshire (the accent shifts into American when she crosses the Atlantic). 'There are aspects of Stella that I'm familiar with in my own personality. I feel I've been able to make peace with myself more because she's so unapologetic about the island that she is.'
So... does Anderson consider herself a solitary person? 'Yeah, I mean my [romantic] partners have consistently said, "You live this life I have no idea about." The idea of saying [to them], "I'm thinking about doing this film, let's talk about what it means for our life"...' Anderson pauses; the corners of her mouth twitch. 'It's challenging for me. It's not my first instinct. My first instinct is to decide, "Can I do this? Yes I can."
It was through work that Anderson met her first husband, art director Clyde Klotz, with whom she had a daughter, Piper, in 1994, when she was just 26. She returned to work on The X-Files 10 days after giving birth. 'I was living practically on set in my trailer with very little time off. So my daughter's life was in my trailer. We took out some pictures recently of Piper when she was little and there were lots of her, at six months old, next to lots of aliens.'
The couple divorced after three years and a second marriage, to documentary-maker Julian Ozanne, ended after two. Her latest relationship, with businessman Mark Griffiths, produced her two sons, Oscar, eight, and Felix, six. She admits her approach to motherhood was, and is, different the second time around. 'I very deliberately make decisions about work. I'm quite adamant about it in terms of working out schedules, pre-agreeing 100%
to do something, because there's only so much time I'll be away [from home].' Although they split in 2012, the couple continue to co-parent and Griffiths is, Anderson says, 'a very, very good father'. Despite rumours, and the will of a million Mulder and Scully fans, she is not dating her co-star of old, David Duchovny, and is currently single.
As an interviewee, Anderson is a curious mixture of brutal honesty and whimsical charm. She has a ready wit and a nice line in self-deprecation, and yet she also wants to ensure she gets her point across, stopping and starting a sentence several times over until arriving at precisely the right words. When she orders a coffee, she ensures the waiter understands that she wants a jug of 'cool, whole milk' on the side.
Anderson is polite, but there can be no room for confusion: this is someone who knows exactly how she likes things to be.
She is also astonishingly beautiful, with one of those classic faces that gets better with age - aquiline nose, clear blue eyes, a mouth with a slight kink that only accentuates her gorgeousness.
In an industry that reveres the young and nubile, last year the actress was quoted as saying she went through 'fully fledged grieving over my youth'. Today, however, she insists she's come to terms with it. 'But I've certainly started paying more attention to it than ever before,' she says. 'I'm actually taking care of my skin for the first time. I'm using some of the products I've been gifted over the years rather than waiting until they expire and then throwing them out.'
Unlike many younger starlets, whose beauty seems somehow disconnected from their character, Anderson is in charge of her appearance and knows what to do with it. Her hands are embellished with two discreet tattoos - Sanskrit writing on the inside of her right wrist, the outline of a circle on the side of her left hand although she won't tell me what either of them means.
It's possible this personal discretion is down to her Atlantic-hopping formative years. A decade of international moves (Chicago, London, then back to Grand Rapids, Michigan, all by the time she was 11) saw Anderson - at the time a self-confessed punk voted by her high-school peers as most likely to be arrested - start therapy at 14. 'It kept me sane and alive,' she says now. 'I seriously needed it.' Why? 'I'm not going to get into details... But I find that it's important to work things through as much as possible. To not run, and to try as much as possible to develop healthy responses to things.'
Studying theatre in Chicago gave Anderson the creative outlet she craved and, via a few off-Broadway productions, she was soon offered the part of Dana Scully. Although the success of The X-Files quickly established the 24-year-old as an international star, Duchovny was originally paid significantly more than her. It was three years before Anderson made a stand and was finally awarded the same salary.
Since then, has she experienced much sexism?
'Yes, at various points,  definitely. All over the place, all over my life, I have. And, I at various times, I've played into it. I think it's quite easy, for young women especially, who haven't necessarily established a sense of themselves, of what does or doesn't feel right, what's good attention and what's not... It's difficult until one gets older to start to draw those boundaries. At the beginning of The X-Files, the pay disparity was massive. But that happens all the time in Hollywood. It’s, "Do this for me, I'll get you a job." All the stuff in the papers today about people in entertainment who have abused their position...'

Referring to the slew of once-loved personalities now facing historical abuse charges, we are quickly entering into darker territory. Anderson is clearly not one of those women who might shy away from referring to herself as a feminist, and she's on a roll: 'It's built into our society. It's easy to miss and it's easy to get used to it. There are things that are intolerable in today's world, in terms of the perception of women. Whether they're Vamps or Vixens... the expectation that, if a woman is wearing a short skirt, she's "asking for it".'
I wonder what she makes of the fact that we still have Page Three. 'Is that the nude thing? Oh God...' She drifts off, than takes up the thread again, referring to Angelina Jolie and William Hague's recent global summit to end sexual violence. 'That problem exists - whether in war or on the streets or in India. And it does not exists because of women. Period. It's not caused by women.' She holds my gaze for several seconds. The inference, of course, is that it is caused by men but, when I push her on this, she moves on swiftly.
Speaking with Anderson now, she strikes me as a woman who has finally grown into herself. In many ways, it feels as though she has lived two lifetimes: one that began and ended with Scully; another that kicked off later in life and has brought her greater fulfilment.
In part, this newfound acceptance comes out of a period of personal re-evaluation. Her younger brother, Aaron, died of a brain tumour three
years ago, at the age of 30. He had been diagnosed with neurofibromatosis as a child - a rare genetic condition that causes tumours to grow on nerve tissue. Growing up, Aaron had regular MRI scans and lived a relatively normal life but when he was at Stanford, studying for a PhD, his behaviour changed and he began to suffer severe mood swings. 'People noticed,' Anderson recalls. 'My parents flew out. They thought he was having an existential breakdown and finally someone did a CAT scan and from that moment to the moment of his passing, it was three years.'
Aaron was a practising Buddhist. Anderson tells me he dealt with his illness 'with such a state of grace...'. She looks away. 'It had a profound effect on all of us. He was just extraordinary. He made it a lot easier for all of us.' When he died, it prompted a time of personal reflection. 'It did make me change priorities and realise life is short,' she says. 'And that it's important to follow one's heart, I think, and make the most out of the time we have.'
She speaks calmly but her eyes are veiled and faraway.
She allows herself a second to refocus and then turns back to me, a bright smile fixed in place. A waiter comes to tell her that her taxi is waiting outside. She thanks him and gets up to leave, pulling her suitcase behind her as she walks out of the hotel. Once again, she refuses all offers of help. Like Stella Gibson, this is a woman determined to do things her own way.

The Fall returns to BBC Two this autumn.