A campaign for better school meals in the London borough of Merton has also succeeded in convincing local council leaders and caterers that quality must improve.
Following intense pressure from local residents, council leader Andrew Judge has pledged to work with parents to upgrade the quality of the meals served in six PFI secondary schools catered for by Scholarest and 47 primary schools by Initial.
Scolarest will now meet a parent representatives to discuss the concerns, and Initial is advising its client on ways to improve the dining experience.
But vice-chair of the parent pressure group Jackie Schneider stressed there was still a long way to go.
"Even when caterers claim to stick to best practice nutritional guidelines like the Caroline Walker Trust (CWT) - as Initial do - it does not mean that children make the right choices for a balanced diet," she said.
Initial conceded that choice on school menus can undermine nutritional standards. A spokeswoman said: "We are currently working with our suppliers towards the Scottish standard which means that all the food is healthy, no matter what choices the children make."
A spokesman for the Department for Education and Skills said Government initiatives to upgrade the quality of school food will involve input from parents in the future.
Government plans for better school meals include draft minimum nutritional standards (that will be rolled out from September and become mandatory a year later), guidance on catering contracts, funds to upgrade kitchens, and a toolkit to help parents analyse menus and work with schools to improve them.