Anyone meeting Alison Jackson would say either that she doesn't look like an artist or that she doesn't act like one. She has a dyed-in-the-wool grooming, and you couldn't imagine her wearing a smock or a taffeta corset. (I'm consulting my female artist template, here - it is a cross between Barbara Hepworth and Tracey Emin.) There's nothing about her that is shambolic, bolshie or inarticulate - if you were asked which, of any contemporary artist, you'd want as your MP, you'd say Alison Jackson. I don't mean she prevaricates and fudges, I'm talking about an ideal MP - acute, engaged, thoughtful, clear, measured, human, energetic. Oh, never mind what I mean. You'd never be asked that.
Jackson's latest book, Private, continues in the same vein as her TV series Double Take, her adverts for Schweppes (those Schhh ... You Know Who ones), her art installations, indeed, everything she's done, stretching back to her degree show in 1999. She takes a famous person lookalike and photographs or films them doing something - it doesn't have to be compromising, necessarily, it might just be a graphic realisation of a mundane activity that tessellates so neatly with the myths surrounding the person that the tableau feels both strikingly real and comfortingly familiar. Although it isn't either, of course. It's a lookylikey.
Mostly, they are fairly comic - George Bush patting his dog, for ages, in the television series, was a marvellously understated, impressionistic portrait of a complete simpleton; the Blairs, with Carole Caplin, frolicking around a pool, misted in vaguely nauseating sexual frisson, like English people trying to be in an Updike novel, but finding themselves too English. And Chris Evans, rolling about looking drunk - it's not like a devastating attack on him as a person, nor is it meant to be. There he is, just drunk. In the BBC series, he was sitting on the loo chatting to Billie, drinking a Guinness. Even within the fairly narrow margins of what this could mean, there was some critical discord - I, for instance, found this rather a charming portrait of marital ease. Others took it to be a stark insight into his depraved ways.
But that's not the point - the point is that Jackson gives us what we think we know, confirmed, illustrated, there in front of us. There's a kind of impossible satisfaction to it, like being able to mind-read, or see into the future. And then, of course, because it is a setup, and it's less real than even the flimsiest tabloid rumour, it highlights rather starkly the fact that reality and truth have a very slender appeal, set against the visible certainties that you can create with the unreal. It makes you feel the way an excellent novel does, as it ends - a kind of queasy mournfulness that you actually preferred the book to your life.
It plays, Jackson says, to the very nature of the medium: "Photography acts as a teaser, suggesting we can know something that we can never know. And the more we can't obtain it, the more we want it." She adds rather blithely, "I'm sure every celebrity knows that it's not about them," and, in the sense that her interest is not gossip of any sort, manifestly it isn't. But, considering most of these myths and impressions are, broadly speaking, unflattering, wouldn't celebrities object to the use of their image for such a project, even while it had a conceptual basis to which their lives and behaviours were irrelevant? In fact, there's been very little response from these icons. "Of the few people who have made comments, one woman said that she couldn't remember posing for one of my photographs, which was actually a photograph of her lookalike counterpart."
It was while at art school, as a mature student (she worked in television for 10 years), that Jackson had this epiphany about photography. Back then, she had a thing for religious iconography that has segued, naturally, into her current fixation with celebrities. "I did versions of Leonardo da Vinci's Last Supper, and they were living performances, but they were utterly still. So they were three-dimensional, obviously, but when you looked at them, because they were so static, you thought they were photographs. At the same time, I was making photography look three-dimensional, and exhibiting my live performances next door to my photography. It was at that stage I realised it was easier and more seductive to look at the photograph. And then I saw that the power of photography was just phenomenal ... If I take a photograph of someone, and put it beside them, you want to look at the photo, not the person. You want an object, I suppose is what I'm saying, you don't want to have to deal with the subject. I think this is what's behind throwing eggs at David Blaine. We were essentially trying to vandalise him, which you can with an object, but you couldn't with a subject. Why else would we try to defile him?"
Jackson first sprang to notice as a result of a semi-scandal surrounding her portraits of a lookalike Di and Dodi, pictured with a mixed-race baby. "When Princess Diana died, people said they mourned her death more than their own relatives'. But they only knew her through a set of images. And I thought that was an extraordinary gap. So I just replace Diana - would people actually mind? And all those questions: was she pregnant, was she going to marry Dodi? That's where those images came from. There was an absolute outcry at the time, some people found it disgraceful and tasteless, and the only reason they found it disgraceful and tasteless was because of the idea of a mixed-race child entering into the pure-bred British monarchy. It was all just completely, wantonly outrageous, it was just racism. What else can you think?"
This was when Ann Widdecombe came out with the hilariously clunky description of Jackson as a blot on the face of Tony Blair's cool Britannia, though it was on the basis not of the portraits, but of a film of the Di lookalike, commissioned for an art installation in Leicester Square, which Jackson says Widdecombe (how could it be otherwise?) hadn't seen. "It was a single, slow-motion image; I just panned the camera up and down a lookalike Diana's body, with all her clothes on, but because it was so slow, it suddenly seemed very sensual. You start to look at the pores in her hand, you run the camera across her lips, it's sensual. Anyway, it got banned. They said that it was some kind of Sharon Stone analogy - I mean, she was crossing and uncrossing her legs, but you couldn't see anything. It made people aware of their own voyeurism, that they wanted to look up Diana's skirt. I'm not interested in seeing anything rude."
It was as a result of this notoriety that the Schweppes contract came about; they wanted to use the lookalike concept, but not for the unsettling ambiguity so much, more to sell tonic water. "I was really worried, really, really, really worried, because I'd left all that commercial stuff to go through this hell of art college, and I'd created this new concept that I was working on and was fascinated by ... I didn't want it ruined for me. But in the end, it was brilliant, I really enjoyed working with them. The work changed, obviously, the readings of it changed. Art work is inconclusive. It opens your mind up. At least, that's what I hope it does. And advertising, using exactly the same photograph, closes things down. It makes it conclusive. It sells a product, and that is its primary function."
Besides which, if she hadn't worked with them, someone would have pinched it anyway, probably. Look what happened to Gillian Wearing (a campaign stole her adults with kids' voices idea and when she threatened to consult a lawyer, they said the only reason it wasn't more like her work was that they'd already consulted one).
Jackson has a very detached aspect when it comes to current affairs - "I'm really interested in how we view the public figure, what makes a public figure, what makes a celebrity, and how images make politicians, so I take an interest in politics, but it's really an interest in the image."
She's the only person I've ever heard talking about September 11 in a conceptual way. "It was a visual bomb, from a country that doesn't permit images. Because Bin Laden's culture doesn't permit the worship of images, they understand how powerful images are. We wouldn't have thought of creating a visual bomb. In a way, he's chopped down two iconic buildings, and used our very truth imagery, to express himself. It's fascinating ... I mean, dreadful."
In a totally different way, that is what these photographs do - set off a tiny, confusing explosion of recognition and non-recognition; Elton John having a colonic irrigation, the Duke of Edinburgh looking at a naked lovely, Tony looking down Cherie's bikini. It's fascinating ... I mean, dreadful.
· Private, by Alison Jackson, is published by Michael Joseph at £14.99. To order a copy for £12.99, plus p&p, call the Hlcarpenter.com book service on 0870 066 7979.