The night before, their perfectly executed main show elicited audible sighs of pleasure. The collective sense of anticipation for this follow- up event is almost indecently visible. After braving my way through the fearsomely tight, wall-to-wall security, I end up where everyone else wants to be: backstage.
With half-an-hour to go, no one wants performers being put off their stride by a journalist asking questions, so I'm trying to be unobtrusive while discreetly taking notes. Chief among them is: "What possessed me to commit such a serious fashion crime?" My Nicole Farhi suit - bought in the sale, I hasten to add - fits like a glove but, horrors, it's midnight grey and everyone is in black.
The entire team troops back from the last-minute run-through wearing blue polythene over their shoes. (The floor has been painted a shade of something lying between apple and Fifties bathroom green, and it must look pristine for the main event.) Hairdressers make final adjustments, clothes are tweaked and then, 15 minutes before lift-off, Vicky Featherstone, the show's director, sidles up and says, "I'm sorry, but you'll have to go now, we're going to do a vocal warm-up." Pardon? This has to be a first. We're talking about a fashion show here.
Since when did models use their voices? I mean, 15 years ago when the model-turned-actress Andie MacDowell and her lovely hair graced the silver screen in Greystoke, her voice was so thin that she had to be dubbed by Glenn Close. But Featherstone is serious. This is no ordinary show. There's no catwalk, no music, no models. Miuccia Prada, the family business's guru, has thrown caution to the winds. She's abandoning tradition by launching her first ever Miu Miu menswear collection with a play, and a British one to boot. So much for the tiresomely common misconception that theatre is unfashionable.
Things don't get trendier than Prada. Whether you're Sigourney Weaver or Julianne Moore, both of whom wore Prada to the Oscars, or one of the thousands who sport or covet the trademark bags and backpacks, Prada is undeniably the chic label of choice.
In the months to come, Prada's art director, David Bradshaw, will create and orchestrate media campaigns to display the variations of the six winter "lines" being heralded here. But on this chilly January night, representatives of five of those lines have become the costumes for the one-performance- only, world premiere of Too Cold for Snow, by a young British playwright, Michael Wynne.
Of course, this is not the first time that theatre and fashion have collaborated. In 1941, Kurt Weill's musical Lady in the Dark was set in a fashion house. Designers like nothing better than the cachet of doing the frocks for plays, and even the Royal Opera House drafted in Giorgio Armani to provide costumes for a (dull) production of Cosi Fan Tutte. But that was merely an add-on. Wynne and Featherstone, the artistic director of the new writing company Paines Plough, had a much more integrated idea in mind.
The clothes have been in the design stage for months, but the show itself was dreamt up and delivered in just seven weeks. Bradshaw's wife, Cathy, saw Wynne's play for the physical theatre company Frantic Assembly, Sell- Out - currently living up to its title on a British tour - and suggested he create a piece for Miu Miu. They then proposed it to Miuccia Prada, a woman known for trusting her own iconoclastic judgement, who gave them the go-ahead.
This decision is less surprising when you know that she not only has a doctorate in political science, but also trained as a mime artist and developed a fascination for the radical - in every sense - theatricality of Italy's most famous writer and performer, Dario Fo.
Featherstone insists that the most exciting aspect of the deal, and the most daring from a commercial point of view, was the fact that at no point did anyone set them boundaries. This project was to be more than a case of hijacking art to dress up a trade show. "We were honestly encouraged to do whatever we wanted," says Featherstone.
Both she and Wynne drew their inspiration from drawings of the clothes - nobody saw the finished items until the day before the show. The easy, adolescent look suggested JM Barrie's Lost Boys in an urban Never Never Land. The fact that it was a winter collection added another element; it had to be short (no one wanted to inflict an entire evening of theatre on a potentially uninterested audience), and they needed to give equal weight to each outfit; hence the resultant ensemble nature of the writing.
With the first draft in place, they cast five actors under 30. Unbeknown to them, Rupert Penry-Jones - about to play Don Carlos for the RSC - had covered periods of unemployment strutting his stuff at previous Milan shows, but all of them were cast for their acting qualities rather than their looks. Indeed one of them, Kelly Reilly, wasn't even a man. When they took the job, all the cast knew about the assignment was that it was to be a week's work with one performance in Milan. Only afterwards did they discover exactly who was behind it.
They certainly weren't prepared for the fringe benefits. After the dress rehearsal - the first time Prada saw what the company had created - Prada was so impressed that it broke its own rules. Freebies for the famous, Miuccia Prada believes, cheapen the image. However, the company was marched off to the main store and, in a re-gendered Pretty Woman, kitted out in presents: everything from underwear to overcoats, at an estimated cost of pounds 3,500 a throw. Even Madonna doesn't get that treatment.
The backstage crew have had fewer than 24 hours to turn a state-of-the- art catwalk space into a theatre-in-the-round for fashion's top 250 movers and shakers. The walls and ceiling are in shades of dove and donkey gray, but "jaundiced" might just be the term to describe the pallor of some of the journalists who have spent the past six days - only one more to go - scribbling style hints and tips and desperately summoning up ever more baroque descriptions of jackets, jerkins, suits, shirts and shoes.
"A friend of mine asked me what it was like," drawls a reporter from Detail magazine to his equally enervated colleague. "I asked him, `What's your least favourite sport?' `Hockey,' he said. `Imagine going to 20 hockey games in a week...'" Consequently, when the play starts in darkness, with a voice-over proclaiming the death of love in a frozen world, you can feel the hacks' hackles rising.
But as Wynne's engagingly benign and touching fairy tale unfolds, the atmosphere begins to thaw. Five minutes in, the gun-toting wannabe gangsters are shown to be increasingly ludicrous and jokily inept - and suddenly the laughter starts and everyone relaxes. By the end of the show, as love returns and violence disappears beneath falling snow - courtesy of the props man at La Scala - everyone applauds happily.
Alexander McQueen may be making his shows increasingly theatrical, but this collaboration is in a different league. Take the clothes away and the play still exists. The following morning it makes the front page of every Italian paper, but even at post-show dinner at a local family restaurant the night before - think of the final scene in Big Night - Miuccia Prada was talking about developing the piece into a full-length play for London.
So it may not just be the clothes that you finally get to see. And, let's face it, a theatre ticket is a helluva lot cheaper than a Prada outfit.