As the supermarket scene of the '70s exploded, so did the ability for consumers to buy Christmas rather than make it. From artificial trees and plastic tinsel going on sale to the first-ever chocolate advent calendars hitting the shelves in 1971 and the new freezer stores packed with frozen turkey roasts, the decade saw a Christmas shopping revolution. In the kitchen, chef Rustie Lee rustles up vol-au-vents and Brussels pate, and tries out a Bird's trifle kit, while in the lab, Dr Chris Clarke finds out why the cheesy filling inside a cheese football snack doesn't go off, how the gooey centre of an After Eight mint is created and why sprouts can give you wind.