Gillian Anderson's face stares out from hoardings advertising subscriptions to Sky television, where the latest series of The X Files is shown on Tuesdays. Terrestrial viewers love her, too: all summer, X Files repeats have been appearing twice-weekly on BBC2. And for the past month, she has also gone solo, reading the runes as the solemn, clinical presenter of Future Fantastic, BBC1's Friday night look into science's crystal ball. One week, Gillian explains how "worm holes" hold the key to time travel, the next she is dissecting the bionic man.
In The X Files she is Special Agent Dana Scully. A cool, sceptical, logical, young woman with science on her side, she plays opposite Fox Mulder (David Duchovny), her impulsive, occasionally gullible, FBI partner, whose instinct is to believe. Together they have encountered every kind of strange phenomenon: werewolves, voodoo spirits, a buried trainload of dead aliens, criminals who come back from the dead, dozens of cloned psychopaths from a failed Pentagon experiment and a pyromaniac whose slightest touch is explosive.
Despite the bizarre cast of extras, this is no cheap American update of Fifties B-movie fodder, but a stylishly shot series that mixes Nineties facts with age-old myths. Its credibility is bolstered by almost daily news of what was once considered impossible suddenly becoming everyday, be it expeditions to Mars or another extraordinary advance in medical science.
But the most extraordinary aspect of this sci-fi hit is Anderson's own meteoric rise. What is it about her that has spawned a vast, global conversation on the Internet among the "Gillian Anderson Testosterone Brigade"? Why does this particular brand of nerds spend hours discussing her eye colour (hazel), what she eats for breakfast (muesli and Multi Grain Cheerios) and whether she has ever had an affair with an alien (no). What made 10,000 fans turn out to see her in Melbourne last month and become so frenzied that several were injured?
She is, after all, no blonde bimbo: her namesake Pamela can relax - there's no competition. She herself admits: "I was convinced that they were looking for someone leggier, with a bigger chest." We've rarely seen Scully's severe outfits unbuttoned, let alone glimpsed her swimsuited. Sex? A screen kiss would be a fine thing.
Gillian Anderson is admired and desired for unconventional reasons. Most of all it is the quality of Dana's role. She has said that she was delighted to find a part which "for the first time in a long time involved a strong, independent, intelligent woman as a lead character".
As Dana Scully, Anderson is an awesome woman of the Nineties, sophisticated, capable, unflappable. This is a gender-bender role: as the male Mulder gets into a twist over his intuitions, Scully is calmly collating data and firing off logical explanations for the phenomena they encounter.
She wouldn't be freaked by a spider or an alien: she'd want to cut them up. In fact, as a forensic pathologist, she is very free with the scalpel. Rarely does an episode pass without Scully slipping into her plastic gloves and white lab coat, bent over rotting flesh. She has already dissected an orang-utan, a body containing prehistoric worms, a victim who died of extreme sexual excitement, sailors whose bodies turned into salt, at least a dozen bodies boiled in a pot and the cavernous interior of an elephant.
She has power over death. That is an important source of her appeal. We live in an age of psychological salvation, constantly told that the answers lie within, not in some incredible, external deity. But who among us can claim absolute success in this internal search? Dana Scully and Mulder, in examining the truth beyond, once again legitimise the age-old belief that the answers lie beyond ourselves.
We have seen Scully, for all her scepticism, in a near-death experience, lying in a boat, drifting across a lake, tied to the bank only by a weak thread, eventually drawn back to life by the voice of a mystery nurse, a latter-day guardian angel.
Scully is cast as cool in the face of danger. She doesn't brawl, she doesn't even kick. She uses her head. Last week she shot a werewolf. She even winged Mulder on one occasion, when he got too aggressive after being doped with an hallucinogenic. But she is also a New Ager, caring and sympathetic. When Mulder is tormented by the loss of his sister, who was supposedly abducted by aliens as a child, Scully comforts him, rescues him psychologically.
But in the safe-sex Nineties, their relationship is hands-off. Never bedded, the pair make tantric sex look like a quickie. To go further would be a huge anti-climax and destroy an aura. This sexual teasing is typical of a genre, recalling the early episodes of Moonlighting in which Bruce Willis and Cybill Shepherd flirted and teased, but did not consummate their relationship. Likewise, the Avengers, John Steed and Emma Peel (always called Mrs Peel), fought crime in an intimate partnership but remained devotedly chaste.
And so The X Files, with its religious undertones, seems to characterise Scully as a sexy, but celibate modern saint, in touch with another dimension, with a sense of humour that's as dry as incense.
All of which is a lot for the real Gillian Anderson to live up to. Is she like Dana Scully? The question would be irrelevant, but for the fact that her following is immense and obsessive and knows her only through that role. Her fan club seems to have an insatiable appetite for personal details. During a recent Internet conversation with 85 fans, she was asked about her favourite music ("Alanis Morrisette, Portishead, Counting Crows, Mozart, Miles Davis, Dead Can Dance"), what she was in a previous life ("an iguana"), what she was wearing at that moment ("long skirt and cashmere sweater") and her daughter's middle name "Maru, its Polynesian".
She has a surprising past. Between the ages of two and 13 she lived in Crouch End, north London, where the hill around Alexandra Palace is as close as most people get to outer space. Her husband is Clyde Klotz, assistant director of The X Files, to whom she had been engaged for a period "shorter than a month, but longer than a week". They were married on the 17th hole of a Hawaiian golf course - not by an alien, but by a Buddhist priest. And Anderson, shedding her alter ego's chastity, duly conceived on that rapturous wedding night. Their daughter, Piper, is nearly two.
The marriage was not the first time she broke with convention. Fresh from Crouch End, having been teleported to Grand Rapids, Michigan, at 13, Anderson became a punk. At 14, she duly lost her virginity to a punk musician 10 years older with a precocious speed that would have produced a frown from Scully.
And then she went off the rails a bit. She was voted Most Bizarre Girl, Class Clown and Most Likely to Go Bald at school because of her weird hairstyles. In a recent interview she said: "I'd been a good little girl in corduroys and plaid. All of a sudden I bought those red shoes, which were the rage in London, put red dye in my hair, started to wear funky mini-skirts and gradually progressed to more outrageous outfits. I felt I was being creative for the first time. My parents were scared I'd get hurt or in trouble, but they allowed me to be independent and whatever I needed."
Acting eventually calmed her down. A film producer's daughter, she spent some time at the National Theatre in London and was a college student at the Goodman Theater School in Chicago. After that she moved to New York and was in a couple of successful plays off Broadway. And thence to Los Angeles. Television was not her ambition: she had a rather British disdain for working away from the theatre. Nevertheless, she took the X Files part three years ago, despite expectations that it would flop and in the face of opposition from Fox Television executives who wanted a more bimboesque woman for the part. She is now on her fifth series and virtually set up for life.
She has been open about her difficulties, particularly with alcohol, when she was younger. Still only 27, she has said: "I'd say for kids the time between 11 and 28 is really hard."
She has been heroic in managing motherhood and her career. When she became pregnant with Piper, The X Files was just becoming popular and its makers were furious. She carried on with the pregnancy and missed just a few episodes, in which interlude Scully was said to have been kidnapped. When she returned to the series, she was very pale: hardly surprising since only 10 days earlier she had delivered by caesarean section.
She seems to share Scully's dry sense of humour. Dubbed by some the "thinking man's crumpet", she has responded: "Well that's better than the lobotomised man's crumpet, I suppose." When compared with Pamela Anderson, she said: "Pamela Anderson is famous for her body. If it is her body, that is."
She is calm about her iconic status. "It's something I certainly didn't expect. Especially with Scully. She's independent and she's passionate about her work. The character is not just a little bit of those attributes, she's very much so. I find it terrific that some people find that so stimulating." But it must get scary at times. One obsessed fan has requested, over the Internet, information on "what public figures would Gillian Anderson actually like to have an affair with? Are any available? Can we film this?"
Is Gillian Anderson really like Scully? "I think," she has said, "that I have a tendency to get as single-minded and obsessed with my work as Dana does, but in a different way. She's a medical doctor and an FBI agent and I'm an actress."
And what about the most important question of all, UFOs and the paranormal? On this Gillian Anderson breaks with her ever doubting television character. "I do believe in UFOs. I do believe in certain paranormal phenomena, like ESP and psychokinesis. I've always been fascinated with it and, I think, on a certain level. I've just known or assumed it to be reality." Dana Scully would be horrified.