It lifts. It slims. It smoothes. And it's set to be the next fashion must-have. Bryony Gordon is the first woman to wear it - and is amazed at the results Forgive me if this reads like the work of a woman who is irritatingly self-confident, verging on arrogant. It is not my fault; the fault lies with the dress I am wearing. On an average day, I have a healthy self-loathing for my body. Like many women, I curse at it, torture it and, above all, wish it wasn't mine. But then I was asked to try on Marks & Spencer's new "Magic" dress and, in moments, a £75 piece off material did what years of dieting couldn't: it made me love my body. Let me explain. M&S is the place to go for body-shaping underwear that sucks in your stomach and shapes your thighs, and now it has gone one step further and built the technology into outerwear - skirts, jeans, tops, dresses - too. But unlike the underwear, which usually resembles something your grandmother might choose, this stuff looks quite good. In fact, the dress has something of Roland Mouret's Galaxy - the frock that caused such a stir last winter - about it, which is apt, because Mouret's creation also incorporated body-shaping technology. Thankfully, the M&S Magic range, which hits stores in September, will cost a fraction of the £800 price of the Mouret creation, ranging from £35 to £75. The magic ingredient is a layer of polyamide and Lycra, which hugs and streamlines the body, making you "slimmer in seconds". And it does. It really does. The dress, which is in a Prince of Wales check, might look grey and drab on the hanger but, once on, it is gravity-defying. As soon as I am zipped in, I am transformed into the kind of woman you might reasonably expect to be painted on to the side of a B52 Bomber. It pushes things in, and then it pushes things up. I have no idea where all the excess wobble vanishes to - this is a magic dress after all, the sartorial equivalent of David Blaine - but vanish it does. At first, I am struck by my breasts (and as the day wears on, I realise that I am not alone in this). They are pushed up and pert as never before. And then I notice my waist, now nipped-in beyond recognition; if not flat, my stomach is certainly flatter. To complement these, I have developed a bottom like J Lo's. I am shaped like an hourglass. There is, of course, a price to pay for this transformation: the dress isn't exactly constructed for comfort and the built-in fabric makes it rather hot and sweaty for mid-summer. But we must suffer to look good. It certainly forces you to sit up straight and walk tall, and its tightness makes it impossible to take steps longer than a pigeon's - the combined effect of which is that I look like a proper lady, almost a femme fatale. I feel that I should be seductively sipping a cosmopolitan in a hotel bar, while jazz strikes up around me. However, I am not. I am in the office loo, feeling rather dazzled by my appearance - I live in a uniform of jeans, vest and battered pumps, and am not used to looking like this. My colleagues are dazed and confused by the transformation, too. As I go back to my desk, feeling a bit self-conscious, somebody wolf whistles. At lunch, men stare at me quite brazenly. I find this embarrassing; my colleagues find it amusing. "What am I? A piece of meat?" I wail dramatically, as a passer-by fixes his eye on me. After a while, though, I get used to it. I even start to enjoy it. In the evening, I have to attend a drinks party for work. I board the packed Tube, drop my ticket on the floor, then panic at the prospect of having to bend over to pick it up, but I am cheered when a young man saves me from this indignity: he not only hands me my ticket, but offers me his seat. Women, too, seem entranced: during my 45-minute journey, three ask where I bought it. When I tell them, they reel off like spinning tops. At the party, I bump into an old male acquaintance, whom I shall call Andrew. In the 10 years that I have known him, the attention that Andrew has paid me has been purely platonic; and, now I come to think of it, often quite hostile. But tonight he embraces me, holds my hand and refuses to leave my side. "There's something different about you," he says, staring at my chest. "Is it your tan?" I don't pay for a single drink. At some point, an inebriated man grabs me and tells me something that, frankly, is not for repetition. Another man, whom I have been talking to about work, hands me his business card and tells me to call him. "I'd like to talk to you again," he says. "But not about work." By the end of the night, I have obtained a mind-boggling 10 phone numbers. Ten! That's an entire year's strike rate in one night. The next day, it is back to jeans, vest and pumps. It is all a bit of a comedown, really. Nobody notices me. I stand squashed in the Tube all the way to work and I imagine that if I do call any of the 10 numbers I have collected and present the men with the real me, they will be bitterly disappointed. I am supposed to send the Magic dress back to M&S this afternoon, but, between you and me, I don't think I will. The Magic range is available in M&S (0845 302 1234) stores from September, but readers of The Daily Telegraph can reserve the dress - which also comes in black and red, in sizes 10-22 - online, at www.marksandspencer.com.