Firmly in the tradition of the fashion business, which is like no other in its use of the last minute, the shop was still being fitted at this point. But, undaunted, the expensively dressed guests, carrying glasses of fruity fizz (peach juice mixed with sparkling white wine), kissed the air beside each other's cheeks and dutifully browsed along the empty rails (upstairs and down). And everyone agreed, above the clumping of the hammers and the whizz of the drills, that it would be very nice when it was finished.
If you don't know Dolce & Gabbana, the chances are you know some people they dress. They are tailors by appointment to the rockristocracy - Bowie, Jagger, Sting. Madonna, in particular, is a big fan.
Dolce & Gabbana have also been associated with looks - grunge and hippie chic in particular; also bra prominence - which have spilled down on to the high street and into the wardrobes of people who aren't necessarily millionaires. The revenues of their retail business for 1994 were estimated at $125m. It's clean money, too. Last year, the Italian government launched an investigation into tax-dodging in the fashion industry. Dolce & Gabbana say they were not even contacted by the authorities.
Next stop for the shopfitters is New York in early 1996.
The pair, who are only 31, owe their pre-eminence and their profile, in some degree, to a lot of catwalk palaver and general mischief. Their fashion shows are regularly described as "theatrical", which means they involve things like lesbian wedding scenes, with Claudia Schiffer in the bridal gown.
If St Michael is the patron saint of Underwear, Dolce & Gabbana are the patron saints of Underwear-as-Outerwear. Their interest in visible female undergarments - basques and bras a speciality - got them branded as pornographers at one point. Their unflustered and immediate response was to create Y- fronts for women - huge great things, thick as carpets, in grey ribbed cotton, and not so much PC as PE.
Meanwhile, their suits - for men and women alike - modelled on traditional Mafia-wear, failed to go down well with the widow of an assassinated judge, who complained vigorously at the pair's tastelessness.
This season, the pair - who are a partnership in both the business and the personal sense - are using themselves as models for their advertising campaign, in which they are seen standing barefoot on two small rocks or leaning against each other, entertainingly po-faced. It's a promotion which seems intent on establishing them as the Gilbert & George of the fashion world.
I meet them at their hotel on the morning of the premature shop-launch. I cannot speak Italian, so our conversation is refereed - with, on all sides, much smiling, nodding and mutual incomprehension - by Carla, their assistant, who seems to occupy something of a benign, motherly role in relation to her employers. She unfurls their names as she introduces them in a manner indicative of vast pride.
Stefano Gabbana is wearing a dark suit and the crispest white shirt ever seen. He is shockingly, animatedly handsome, in a way which photographs of him seem to blank out. He appears to be the talker, the energy.
Domenico Dolce wears a leather jacket, pinstripe trousers, a black woollen hat protecting his virtually hairless head. As he talks, his head is lowered, his shoulders slightly rounded, his hands are folded together in his lap and he looks at you shyly from the corner of his eyes. This is in stark contrast with his tendency to affect a comical, rumple-browed sternness in front of the cameras.
Unlike Stefano, who had arrived the previous evening, he had only just flown in and was slightly late after circling tediously in a holding pattern above Heathow. Up there, he had read, all the way through, an article in an Italian magazine about Duran Duran. He was that bored.
Stefano was born in Venice but moved to Milan and went to art school where, studying graphics for advertising, he had no thoughts of becoming a fashion designer. "My mother was a housewife, my father was working at an industrial company in Milan," he says. "There was no talk of fashion in our house. But I always liked to dress myself - Fiorucci, which was not very expensive but very fashionable; Lacoste T-shirts; Levi jeans."
Domenico, who grew up in a village near Palermo, Sicily, was a tailor's son. Asked what age he became interested in his father's trade, Domenico thinks for a minute and says: "At seven."
They were both assistants in a Milan design company and went into business together in 1981, initially as consultants to big, factory labels. "We had no money at all," Stefano says. "We lived in one room of a small house, where we worked, ate, spent the whole day. There was an oval table which opened up. It wasn't even stable." Finally, though, they were one of three new designers given their chance during Milan fashion week in 1985.
Subsequently, in the fame of Dolce & Gabbana, in the degree to which their names have leaked from the fashion pages, it is Madonna who has played the pivotal role. During the documentary film In Bed With Madonna, Warren Beatty goes backstage with a present - just a little several-thousand- dollar something - and it's in a Dolce & Gabbana box. "We knew absolutely nothing about it," Stefano says. "One of our friends came back from New York and told us. We didn't believe him. Even when the movie came to Italy, we didn't believe what we were told. We were the last people in Italy to see this movie."
Madonna did the pair another favour shortly afterwards, appearing prominently at the Italian San Remo festival in a Dolce & Gabbana dress at a time when she had a relationship of sorts with Versace. "She had a Versace dress and a Dolce & Gabbana dress, and she chose the Dolce & Gabbana," Stefano says. "Suddenly, I see Madonna on the front page of the Herald Tribune." Stefano gives a suppressed smile. This is clearly his idea of the best sort of mischief.
As, presumably, was the party the pair threw in Milan in 1992, timed to clash with and upstage a show of the latest from Emporio Armani. Dolce & Gabbana sent out an invitation promising "a small and very private dinner with Madonna". In the event, guests were treated to a finger buffet in a cavernous nightclub, with Madonna cordoned off on a balcony. Dolce & Gabbana are mild and cool, but clearly they have never lacked what it takes.
It was reported this year that Dolce & Gabbana had contacted Sharon Stone to ask her if she would wear their clothes at the Oscar ceremony, an increasingly desperate designer battleground. They deny this and, in fact, come over rather humorously indifferent at the thought. "If they like the dresses and ask for them, we send them. But we don't send out hundreds of pieces like most of the other designers do. We only wait for requests. And then, if they ask, why not? But it's personal gratification more than anything."
Domenico once cast a look at the ankles of the fashion director of Esquire magazine and informed him, "Only bus drivers wear short socks." This was pithy by comparison with some of the duo's many pronouncements on their work and how we are to understand it. In 1993, they declared that their menswear collection was styled for "a traveller of the soul, looking inside himself in order to find an answer". There was no clear indication of what the question was to which Dolce & Gabbana man was so deeply seeking this answer. But given that this was the collection which featured the first ever appearance of the male sarong, perhaps we can infer that fairly high on the agenda would have been the question, "Would I dare go out in a woman's wrap?" And many men would have been forced to conclude that they wouldn't get 10 yards dressed like that - even 10 yards into their own souls.
Their drop-out look for spring 1993 - Woodstock beads, bell bottoms, tie-dyes, centre-partings - was, they said at the time, a set of creations for "a hippie of high fashion", which seemed to be wanting to have it both ways. But then again, wilful perversity is what the fashion industry has by way of a creative principle. And Dolce & Gabbana have wilful perversity in spades.
"We like the feminine side of the man and the masculine side of the woman," Domenico says, referring in part to their fascination for the singer kd lang, whom they clothed for the Princess of Wales's Concert of Hope last year at Wembley Arena. Nowadays, the pair may appear blithe about whether or not the stars grow attached to their creations (that much easier to manage when the stars attach themselves so assiduously), but at that time, their company was not slow to seize on a PR opportunity.
I was on a list of reviewers for that Wembley show and, accordingly, received a phone call in the week preceding it which went something like this: "This is just to let you know that at Wembley, kd lang will be wearing Dolce & Gabbana. Would you like me to spell that for you?"
The lang dress turned out to be white and long and was described unfavourably by one commentator as "the Turin shroud". Others remarked its close resemblance to a hospital theatre-gown. "She was the one who chose that outfit," Stefano says "We sent her several sketches. Some of them we had made thinking about the music of the Fifties, because we knew that she could sometimes look like Elvis and was interested in dressing in a masculine way. But she chose this one. You can never know with people."
The Sloane Street store, like all of the Dolce & Gabbana stores (Singapore, Hong Kong, Seoul), matches in detail their main Milan store. They tell me that the smallest changes made to the design of the main store are directly and faithfully echoed in the other shops. We're talking hand- decorated, light-coloured marble flooring, patterned with rampant lions; palazzo-style room succession; sandstone walls and ceilings in terra rossa and pastel ochre; and white plaster cornicing which, according to the literature handed out at last week's opening, "exalts and embodies the impetuous whiteness of the other rooms".
Clearly some shoppers are at home here, but it's the kind of surrounding that can also make for a buttock-clenchingly intimidatory experience. There's only so much impetuous whiteness a person can take. I wondered what the setting of the shop was intended to convey to the shopper, entering for the first time. Both spoke at once on this theme, with Carla presenting a kind of edited remix.
"We are very much tied to traditions, but we are very young and modern at the same time. We want people to know who we are and to transmit our tastes and our ways of working. People entering the shop should share and understand this atmosphere. They should understand what we love and what are our passions. They have to breathe this kind of air."
We all nodded and smiled enthusiastically at each other, as if that really nailed it.