This season, Roksanda Ilincic decided not to have a show, “but it comes with exciting news,” she said, “and that is that I’m opening a popup in Sloane Street. Next to Chanel and Pucci. It’s amazing. And the space is huge.” I went to see her in a light-filled penthouse showroom next to the storied Museum of the Home, (set in a series of restored 18th century almshouses) on the Kingsland Road in the East End of London.