Since its inception in 1707, Fortnum & Mason has become the premier department store of the British élite. A browse through its six-floor building on Piccadilly in London's West End shows why: there you can buy rose-petal jelly, a black leather Scrabble set or a $40,000 Christmas hamper containing a tin of beluga caviar and hand-engraved stationery delivered by horse and carriage.
Yet despite its flair for conspicuous consumption, F&M has struggled with "customer circulation," says marketing director Alison Jordan. Many shoppers visit only during Christmas and Easter, and most never venture beyond the food hall on...