The stark message from Jamie Oliver’s televised campaign was not just that even the most reluctant of children can be persuaded to eat greens, but that feeding children with burgers and pop can fuel hyperactivity and unruly behaviour. Better still, Welshpool high school, in Powys, beat the celebrity chef to it in demonstrating that dietary and nutritional standards can be transformed. It opted out of the authority catering contract five years ago, sources local produce and uses a swipe card system that allows parents to block unhealthy purchases by their children.

The results are mouth-watering: intake of fries down by three-quarters, turkey burgers down by two-thirds, cola replaced by fruit juice, water and milkshakes. Children are queuing up to eat home-cooked food. The cost is pound;1.70 a meal. But the cost of not doing it - junk-food-fuelled children who cannot concentrate in class - may be much greater.