Recently, however, views have begun to change as industry experts have realised that large stores work for both digital and traditional shoppers. General e-commerce wisdom suggests online shopping is at its best when goods are dispatched from centralised warehouses. Food retailing is different, however, because so much of it is perishable and profit margins are very low. Smaller warehouses attached to existing stores are often more cost-effective, allowing supermarkets to serve old-school and online customers from one site. As this realisation sets in, the big beasts of food retail are looking at their estates with new eyes, seeing big stores as key to their future rather than dinosaurs past their sell-by date.