But the move to tackle unhealthy eating among children has been overshadowed by a row over the way the Government will make caterers choose the “healthy” menus.

The Government favours menus with a balance of broad food groups (“meat and fish”, “bread and cereals” and so on). But nutritionists have challenged this approach, saying that each menu should instead meet more rigorous standards, based on the amounts of essential nutrients. For example, each meal might have to contain a minimum amount of each vital vitamin and mineral).

Jane Landon, policy communications officer of the National Heart Forum, said:

“Health professionals support nutrients - the catering ndustry supports food groups because they’re more pragmatic. But who would you rather listen to about children’s health?”

Meanwhile, MPs at Westminster highlighted concern over low take-up of free meals by pupils who fear being stigmatised as poor. With some schools still making pupils queue separately for free meals, MPs on all sides called for systems to protect the anonymity of those children.

In Derby, the use of smart cards, guaranteeing anonymity, resulted in a 20 per cent increase in the uptake of free meals.

MPs also raised concerns about the wide variation in standards of meals, and dingy canteens.

Guidance on food standards will be issued in autumn, with regulations taking effect from April - 20 years after they were abolished by the Tories, schools minister Jacqui Smith told MPs.