Just when you thought the Fortnum’s Christmas tale was complete, the shop quietly unveiled its most spectacular secret in centuries. Hidden for two years behind a cheerful Zebedee Helm collage, a brand-new Double Helix Staircase has now risen at the heart of 181 Piccadilly. Inspired by Leonardo da Vinci and hand-built by master craftspeople in Sussex, it is part architectural marvel, part swirling artwork, and entirely Fortnum’s. This unexpected addendum returns us to Piccadilly for a second helping, celebrating a staircase that is already becoming a landmark in its own right.