Inside the Factory: Crisps

Gregg Wallace follows 27 tons of potatoes from a Hampshire farm through the world's largest crisp factory as they are peeled, sliced and fried to make more than five million packets every 24 hours. Cherry Healey discovers the special varieties of potato that are grown to make the snacks, as well the surprising ways that brains can be tricked into thinking a crisp is crunchier than it is. And historian Ruth Goodman investigates who invented the crisp - was it the Americans, as is often cited, or the British?