At this stage in the Kraft-Cadbury stand-off, it’s all about air – and not just the hot variety, although there is plenty of that around too.

Cadbury measures volume by weight, which means that additional sales of the bubble-filled Wispa don’t contribute as much to the volume figure as sales of that solid old favourite, a slab of Dairy Milk chocolate. But margins are likely to be higher on the Wispa and on other newer products, such as loosely packed bags of crispy chocolate-covered Clusters (which you could make in your kitchen but Cadbury has cunningly persuaded customers to purchase).