You might be surprised to learn that Transport for London has one of the most significant retail estates in the capital by number of units. These units are characteristically small ones, and are located in areas of high footfall, where space comes at a premium and is traded off against operational capacity. The need for innovative design is high, as is the opportunity for retailers that get it right. Having shortlisted 10 concepts, TfL this week announced Sook as the winner of its retail innovation competition. Sook ‘transforms empty spaces into digitally enhanced playgrounds for anyone to use for as long as they want’. More specifically, Sook’s proposition is built around a customisable ‘digital wallpaper’, which allows pop-ups to quickly and cost effectively fit out a unit digitally. Rather than decorating and making good, the technology is demountable; and hence attractive to those temporary operators who want to make a splash without spending a fortune. Areas of transitional high footfall such as underground stations are well suited to brand concepts, where stock is kept to a minimum and engagement / advertising is a core part of the proposition. Digital feels like an obvious solution.