India, June 4 -- Food has long served as a tool of diplomacy, persuasion, and cultural exchange. New tastes have opened markets, forged commercial ties, and familiarised distant societies with one another.

In December 1902, an unusual crowd began gathering every Sunday morning outside Treacher & Company's store in Poona. At eleven o'clock sharp, people arrived carrying coupons clipped from a Bombay newspaper. The promotion had been launched by the confectionery firm of John Mackintosh, the self-styled "Toffee King" who claimed to own the "largest toffee factory" in the world. Anyone presenting a coupon could claim two packets of toffee in flavours of their choice.

Toffees made by Mackintosh's company of Halifax, England, had been availa...