Sitting at a table in a restaurant in Bermondsey, across the road from their studio, Jane says, "We are twins. It's a fact."
Louise rolls her eyes and says, "The next question is: were you monozygotic or duozygotic? Were you one egg or two eggs? When we were born it was the late Sixties, and the only way you could find out was to see if there was one placenta or two placentas. And when we say, 'What was it like then, Mum?' she says, 'It was a real mess!'"
Louise says, "Jane might have been 6ft, and blonde."
Jane says, "Or I might have been a boy, and she might have been a girl." They are small, with brown hair and pretty, babyish faces. Louise wears jeans and a cardigan; Jane's clothes are black. Louise has slightly longer fingernails.
The Wilsons project their video images on a large scale; when you walk into one of their exhibitions, you are surrounded. You are meant to be sucked in and hypnotised. In one film, Gamma (1999), the camera prowls around the shadowy corridors of the abandoned military silos at Greenham Common; in another, Stasi City (1997), the camera prowls around the shadowy corridors of the disused Stasi building in Berlin. Watching these dense, obsessive clips, spooling past the ducts, vents, grilles, shafts, panels and padded doors, the viewer is filled with a sense of mounting dread and alienation. We are beyond irony. Defined in Frieze magazine as "hyper-banality with violent undertones", their work is perfect material for the Turner prize, which the Wilson twins are tipped to win.
When I meet the twins, who are from Newcastle, they are breezy and talkative; they give no outward impression of being the ambitious, dark visionaries I was told about. (People in the art world say they work around the clock and make it their business to know everybody.) They have gentle Geordie accents, and are chatting about Robert Downey Jr. Jane says, "It's ridiculous to put someone in gaol just because he's done a bit of charlie."
We go to a restaurant, where the twins tell me about their lives. They spend hours every day in a video edit-suite, looking at reel after reel of footage and splicing it together, trying to achieve the blend of alienation and subtle horror that is the perfect Wilson twins feeling. They are tired. They have just come back from Las Vegas, where they shot footage of the creepy, neon-decked interiors of gambling halls. The twins have also been filming in the House of Lords. They both have mobile phones. Jane's keeps ringing. She is finalising the details of the catalogue for their exhibition at the Serpentine Gallery next month.
When Louise leaves the table, Jane tells me that she could never imagine working with anybody other than Louise. "With Louise," she says, "I don't have to spend ages trying to convince her that this is how it should be." Louise, she says, is "very good photographically, filmically."
What are the differences between the twins artistically? Jane says, "I would say that Louise is certainly more, um ... it's very hard for me to step outside it and think about it because I'm so bloody close to everything at the moment." Then she says, "It's always interesting, when we're filming, to see what she's pictured and what I've pictured. I will say to her, 'Oh, you went for that corner. Oh, I was going to go for that corner.'" Jane thinks that she is good at "working on details, picking things out". It strikes me that the Wilson twins call themselves "Jane and Louise Wilson". They do not, for instance, call themselves "Louise and Jane Wilson".
The twins do not like to discuss their private lives. They live in Brixton; they work in Bermondsey. They have recently spent a year in Berlin, having won a scholarship from the German government. They frequently travel to Oslo, where they have an arrangement to teach at an art college. They sometimes have boyfriends, although they have never had the same boyfriend. Pondering the question of boyfriends, Louise says, "Well..."
Jane says, "I'd rather we didn't talk about this."
Louise says, "It's quite hard. The people we meet are all from the art world, and artists' relationships with artists are not easy." She looks at Jane, seeking approval. Jane frowns. Louise says, "Well, I'm certainly not un-optimistic."
Having been to different art colleges - Jane stayed in Newcastle, Louise went to Dundee - the twins moved to London in the early Nineties, to take MAs in Fine Art at Goldsmiths College. They began to work together. They were both interested in blown-up images of the insides of buildings. One of the first things they did was to take pictures of the inside of their own flat, and exhibit these pictures of walls on the walls. Louise was, she says, influenced by the stage directions in Harold Pinter plays. She says, "The pail on the floor. I love the economy of that."
Later, they took pictures of the interiors of a seedy bed-and-breakfast in King's Cross, where they lived. The atmosphere of transience, the cheap carpets and peeling wallpaper interested them. Their big break came with Hypnotic Suggestion 505 (1993), a work in which the twins videoed themselves being hypnotised. The girls sit on chairs while a man with a BBC accent tells them that they are relaxing, that they are feeling sleepy. The hypnotist tells the girls to lift their right hands towards their faces. Jane's hand moves quickly; Louise, who appears to be in a deeper trance, sits back in the chair, her hand sticking out at an odd angle. Hypnotic Suggestion 505 was exhibited in Beyond Belief, a 1994 show at the Lisson Gallery in London.
Louise says, "It started with a quote from Cocteau, about all cinema being a form of mass hypnosis."
Were the girls actually hypnotised?
Jane: "How would you define hypnosis? My personal idea is that hypnosis is a very relaxed, very complicit, but very focused state. It's a bit like when you've just been in the cinema and you just..."
Louise: "You just can't relate to..."
Jane: "To the world outside." She thinks for a moment, and then says, "When someone describes that your hand's getting lighter, and it's going to touch your face, when you've got your eyes closed, the thought of trying to get your hand near your face, and to be able to touch your face, is not easy. It's quite difficult."
Nicholas Logsdail, the curator of the Lisson Gallery, tells me that the twins are successful because they have "territory which is their own". The first work he saw, he says, was a black-and-white photograph in which "one of them is trying to drown the other. It depicts both of them battling with each other's psyches."
Who was trying to drown whom?
Logsdail thinks. "I can't remember," he says. Their work, he says, is about "foibles of human organisation, human weakness and human strength". Jane, he says, is "probably more outgoing, Louise more pensive, but that's probably not fair to either of them". One quality, he predicts, is longevity. "The Chapman brothers," he says, "are, I would suspect, not nearly as solid as Jane and Louise. They are as solid as Gilbert and George."
At the time of Beyond Belief, he said, he gave them a piece of advice. He said they were faced with a choice: they could either "ride on the crest with the rest of the YBA gang, or separate yourselves out". He believed it would be to the twins' advantage if they hung back for a while. "We had a bit of a confrontation," he says. "They didn't understand, but they understand it very well now. You don't talk about Jane and Louise in the same breath as Damien Hirst and the Britpop artists."
Jane and Louise take me to their studio building. We visit the exhibition space on the ground floor, a large room in which there is a tent, and a rack of khaki clothes. We look at the items. Jane says, "I wonder who this is."
A woman appears. Jane says, "Who is this?"
The woman says, "Next."
"The clothes shop. This is a presentation."
Jane laughs. She says, "I've done this before. The last time it was Habitat."
The studio is the size of two squash courts, and, of course, has no easels or pots of paint or jars of turps. There is a table, there are some chairs, and there is a television set and video monitor. The twins' studio is next door to Mark Wallinger's. Wallinger was nominated for the 1995 Turner prize for his superb, rather disorientating paintings of horses and jockeys. The twins like Wallinger. "He's gone for a really severe shaved head," says Jane. "He looks like he's done time. Actually, I think it's for a work."
The twins sit down and light up cigarettes. They are, they say, happy. They never expected to be doing so well. They like being part of the art world, with its openings, its parties, its constant supply of intriguing people. (Several people told me the twins love to party.) They like painting, and can talk at length about the history of performance art. They approve of sensationalism. They like Warhol. They were not offended by Marcus Harvey's picture of Myra Hindley, composed of the handprints of small children, but disapproved of the protester who damaged it. "It's not the same as Rauschenberg erasing de Kooning!" says Jane.
They had a normal childhood, they say, in Kenton, a suburb of Newcastle - comprehensive school, lots of friends, stable parents. Their father, Louis Wilson, is a naval architect. Their mother, a Newcastle United fan, took them to football matches at St James's Park. They have one brother, a year older, who is an aerospace engineer. Louise says, "He did thermo..."
Louise: "He's designing a cooling system for the wings of the Airbus."
Jane: "I think he's moved on to fuel."
At school, they had different friends. Louise says Jane's friends were "more sporty". Then she says, "You went to Butlins." Jane says, "That's right. In Filey. It was a bloody nightmare."
Louise says, "Tell him about nicking the Gideon Bible."
"Oh God. The people I was with were so pissed off with the chalet they got that they cleaned the place out."
They were both good at art. Jane tended towards creating images and chopping them up; Louise was "more illustrative". Jane describes Louise's work as "delicate watercolour". I ask Jane if she would describe her younger self as artistically aggressive. "Expressive," she says.
The twins play me a reel of their most famous works. We watch Stasi City. The camera moves around the horrible, doomy looking corridors. The twins show me a photograph of a sculpture they have made. It is a reconstruction of two padded doors. "It's interesting," says Jane, "because there were these padded doors at the entrance to the rooms, but the rooms aren't actually soundproofed."
Louise: "It's like bureaucratic theatre in a way."
Jane: "It was so imposing, so intimidating. To walk through one padded door and another padded door - just the psychology of that was really strange."
The camera pans across a pair of feet hanging in mid-air, as if the body were hanging from a rope. I say, "Who is that?" Jane says, "One of us. It doesn't matter."
On the screen, the camera pans across an area of ceiling with decaying paint hanging down in strips. This reminds me of a scene in another Wilson twins film, Crawlspace (1995), in which there is paint peeling from a ceiling. The difference, says Jane, is that the twins had designed the peeling paint-effect in Crawlspace themselves. "What was so odd about the Stasi building," says Jane, "is that we didn't need to bring anything to it. It was already there."
We watch Home/Office (1998), a film made from real footage taken by the Fire Brigade. There are scenes of burned-out homes, and there are scenes of burned-out offices. The Wilson twins' arrangement makes you think about how homes are different from offices. It is creepy. Louise walks across the studio, and brings back a sheaf of photographs, which she hands me. They are pictures of charred sofas, blackened kitchens, melted appliances.
Next, we watch Gamma. More corridors, eerie noises, a trapdoor. "That's a decontamination chamber," says Jane. "We got that noise by dragging a spoon along the perimeter fence," says Louise.
In Normapaths (1995), a person, on fire, walks across a room. It is a sensationally nasty image. In Crawlspace, we see a haunted house, in which there is a red-painted figurine of Harold Wilson, a lavatory, the belly of one of the twins with sinister growths.
I say, "How much do you sell these for?"
Jane says, "It depends if you're including equipment or not - the projectors and the players."
"But how much, roughly?"
Louise says, "pounds 30,000." They recently sold a print of Stasi City to the Kunsthalle in Hamburg. A large still photograph, framed, of a scene from a Wilson twins film costs around pounds 3,000. They come in limited editions of three.
The work they are currently editing is called Parliament, in which the twins filmed the corridors and walls of the House of Lords and the House of Commons. Lord Freyberg, himself a sculptor, arranged for the twins to have access. Black Rod, says Freyberg, was "fine" about the project. "They work as a pair," he says. "Both at different times become dominant." Jane, he says, was the one who tended to consult the cameraman, to check the angles.
Even so, I have the feeling that Freyberg is wary of saying anything to discriminate between the twins; like anybody who has been around them, he knows how not to offend them. "They were quite good at chivvying each other along," he says. "When one was dragging, the other would say, 'Come on!'" He says that "they shoot from two angles - knee- level and chest-height," and that they were "fairly awed by the whole richness of the decoration".
In the studio, the twins show me unedited footage of Parliament. There is footage of walls and corridors. The place has a slightly sinister, Wilson twins look to it. Then the image goes twisted and fuzzy; the VCR is snarling it up. "It's never been the same since we dropped it," says Louise. She fiddles with the wires at the back of the VCR.
Jane says, "Are you sure it isn't just the back of that lead?"
Louise tugs at the wires. Nothing happens. She says, "Let's just try this." Again, nothing happens.
"It's probably that."
Louise says, "No, it's not coming on."
The Jane and Louise Wilson exhibition is at the Serpentine Gallery, Hyde Park, from 14 September