Known as one of the favourite designers of the Duchess of Cambridge (formerly Kate Middleton), the Brazilian-born Issa has become a mainstay of the London catwalk scene.
She toned down her usually exuberant colour palette, which has always brought a touch of Rio to London, in favour of more muted colours that evoked the American west. But the shapes and cut were glamorous, and knitwear tops that turned into cowl necks and balaclava-style headgear brought warmth and wit to the show.
Of course, she threw in a few sparkly evening dresses, with a plunging neckline or a backless look, to help make cocktail hour sizzle.
Despite leaving behind the fine weather and natural allure of Brazil, Issa said she finds joy in London, even if the weather is often drab.
"Even when it's misty and fog, it's beautiful," she said. "The shades of grey are fantastic. And it's not misty and foggy all the time."
When the weather gets her down, she goes to London's museums for inspiration.
And she gets a kick from being part of an A-list fashion crowd, enjoying a reception Friday night at 10 Downing Street with designer Victoria Beckham, American Vogue editor Anna Wintour and other top figures.
Soon Issa will be off to the Academy Awards in Los Angeles — not the actual ceremony, but, even better perhaps, parties hosted by Elton John and Madonna.
Issa denies designing any maternity clothes for the Duchess of Cambridge, who is expecting a baby in July. But she said many of her stretchy dresses are popular with mothers-to-be.
She followed Jasper Conran, John Rocha, Julien Macdonald and other stalwarts in a Saturday lineup that brought throngs of well-heeled (literally) fashion fans to Somerset House and other locales in central London.
The five-day spectacle continues Sunday with shows by Vivienne Westwood, Temperley London, L'Wren Scott and others.