On a picture perfect spring evening in London, 600 guests clutching cherry-red tickets for Gucci’s show at Tate Modern gathered at the museum’s riverside entrance in their finery. They posed with the shimmering dome of St Paul’s Cathedral in the backdrop of their selfies or commandeered bemused cabbies to capture arrivals by black London taxis. An army of loafer-shod champagne waiters escorted the footballer Leah Williamson to her seat next to the actor Andrew Scott, while the K-pop star Lee Know stopped for a chat with Paul Mescal, and Dua Lipa paused to read the words of Mustafa the Poet, beamed in vast white lettering in a scroll that covered the floor of the Turbine Hall. “Gucci Londra”, staged in one of the city’s most spectacular cultural spaces, was the kind of shiny, glamorous, see-and-be-seen night that has become less common in post-Brexit London. But this celebration of the capital and of British style was staged for the benefit of an Italian brand owned by a French luxury conglomerate. London fashion week’s profile has been eroded with the recent departure of famous names such as Victoria Beckham, who now presents her collections in Paris. Shows of this awe-inducing scale are now far beyond the means of almost all British brands. The museum’s subterranean Tanks gallery was lush and fragrant with 10,000 plants to be donated, after the show, to local community projects. The Venetian musician Yakamoto Kotzuga kickstarted the soundtrack as the first model emerged, wearing baggy jeans with vintage-style patching and thick-rimmed glasses, a slouchy suede blazer unbuttoned over a loose daisy-print blouse. These were laidback clothes aimed at generation Z as they revisit boho summer style. A ballet-pump-meets-loafer hybrid scored murmurs of audience approval, which will be music to the ears of the Gucci top brass, who are battling a sales downturn after a slowdown in Asia. “Englishness with an Italian accent,” according to the designer Sabato De Sarno, who chose London for his first show outside Milan to honour the origins of Gucci. The founder, Guccio Gucci, had the idea for his luggage brand while working as a porter at the Savoy hotel across the river – booked solid this week, with Gucci’s high-rolling clients. “Breathtaking,” was the model and activist Sabrina Elba’s verdict after the show. “In a word? Just, yes!” said Alexa Chung. De Sarno’s mother, with her new Gucci handbag in her son’s signature lacquered red nestled in her lap, dabbed her eyes as Frankie Goes To Hollywood’s The Power Of Love boomed through the room. Tristram Hunt, the director of the V&A Museum, which will soon open an exhibition devoted to Naomi Campbell and an another of photography from Elton John’s collection, said he hoped the night was the start of a glamorous summer for the city. “We all need that brightness, don’t we? And museums are part of that urban ecology, not least because they are such glamorous spaces.” De Sarno’s third show for Gucci showed him beginning to have fun. Where his first collections doubled down on classic simplicity, attracting criticism for underwhelm, this show jacked up the energy: pearl chokers, bugle beaded party dresses, sport socks with green and red Gucci trim, and offbeat colour combinations of mustard with lavender, or lemon with rose. At the afterparty, that let-your-hair-down spirit came served in shot glasses of iced vodka.