The children of Kidbrooke school have had their chips. Great mounds of flaccid reconstituted potato used to be a lunchtime staple at the Greenwich comprehensive, the traditional accompaniment to fish fingers, burgers, pizzas, and all manner of processed meat in funny shapes. Chips were popular -Kidbrooke’s 1,400 pupils would get through a quarter of a tonne of them each week - but now they are no more.

If banning chips was radical, the things that have replaced them have really transformed this school’s dinners. Instead of 15 kinds of junk, now there are just three freshly made dishes to choose from. Today’s menu - slow-cooked balsamic beef with mushrooms and creamy mash, beef lasagne or vegetable chow mein with coleslaw and mixed leaves - reads like something you’d find in a West End bistro, not a south London school.

When it opened in 1955, Kidbrooke was Britain’s first purpose-built comprehensive, the template for a movement that would change the face of education. Fifty years later, a revolution has been hatched in its kitchens that has the potential to be just as far-reaching. Already it has spread to another 20 schools in the borough and, by the summer, it is hoped 28,000 children in 70 schools across Greenwich will be eating healthy food at lunchtime.

And that’s just for starters. The plan is for the project to be replicated nationally as part of a campaign, called Feed Me Better, to retrain dinner ladies, educate children about food and persuade the Government to spend more on school meals. The man with the plan is celebrity chef Jamie Oliver.

“If we can do it in Greenwich on a tight budget, don’t start telling me you can’t do it in Newcastle, you can’t do it in Birmingham. You can do it anywhere,” says Oliver. “What we want is for people to copy it.”

Last April, Oliver spent two weeks at Kidbrooke filming for his latest television series, Jamie’s School Dinners. What he saw was entirely typical of school kitchens up and down the country, but no less alarming for that.

There was hardly any cooking going on. Trays of pre-prepared food were shuttled in and out of ovens, tipped into containers and served up.

Oliver’s ignorance of what he was serving (children couldn’t believe he didn’t know a twizzler from a smiley) is matched by the blank faces when he asks a class to identify a courgette and a stick of celery.

Kidbrooke was chosen from around 100 schools visited by researchers, partly because, with 50 per cent of pupils on free school meals, it represented a typical comprehensive. But it was also because in Nora Sands, the school’s hardworking, talkative, no-nonsense lunchtime supervisor, they found a perfect foil for Oliver. Greenwich was a good testing ground because 81 of its schools had remained with the council’s own school meals service, with just eight in the hands of private contractors.

Headteacher Trisha Jaffe was already looking for ways to improve her pupils’ diet when the programme makers approached her. “A significant number of youngsters were coming in for a plate of chips and ketchup. We were accepting it because we wanted them to eat something, but it was not good food, it was stodge.” She was keen to get involved, but initially she was not sure Oliver was the right man for the job.

“I have been totally won over,” she says. “It was really different from his restaurant, where he has to do 60 covers in three hours. Here you are talking about 600 to 800 youngsters in a 50-minute break. He had a lot to learn, but he has risen to the challenge and I am in awe of what he has done. It’s amazing. It is really good food.”

Cooking with the priority on price rather than taste is not the way Jamie Oliver is used to working. “Normally I say, ‘let’s invent something great’, then find out how much it costs, add 65 per cent and put it on the menu.”

His first attempts came in way over budget, but now Kidbrooke has settled on a menu of 30 different dishes, each costing 37p and selling for pound;1, exactly the same as before.

Mouthwatering offerings such as fish in creamy coconut curry sauce and Mediterranean braised lamb on couscous alternate with reinvented classics such as “proper sausages”, spaghetti bolognese and chicken curry. The magic ingredient, key to keeping the food cheap and nutritious, is the “base sauce”, a blend of finely chopped vegetables hidden in all manner of dishes that gets the children eating healthy food without the “urgh” factor.

Converting Kidbrooke’s pupils has been a battle. At first, unfamiliar dishes were given a wide berth; only when the old menu was abolished did they start to try them. “There are still a group of hard to reach kids,” says Trisha Jaffe. “But we are working on them. And there was a whole set of people who said, ‘this is disgusting, we are not eating it’ who are now quite happily eating it. There has been massive progress.”

Becoming a parent himself was the spur for Jamie Oliver to do something about children’s food in schools. “Bar a small percentage of success stories, kids in schools are not getting what they need,” he says. But parents at Kidbrooke weren’t convinced. There were telephone calls to school asking when they were putting “proper food” back on the menu, or complaining when puddings were taken off the menu (fresh fruit and yoghurt are available instead); some parents resorted to pushing takeaways through the fence for their children.

“You would think parents would be on your side, but of course most of the ones who like what you do don’t say anything,” says Oliver. “And the ones that hate it make it very clear.”

Dinner ladies, on the other hand, love it. “You have 100,000 dinner ladies out there,” says Oliver. “They are all nice, but hardcore genius ones are very few. There is no training. These are women who have been slagged off indirectly for years. When you slag off school dinners, that makes them feel demoralised, worthless. They are not looked after, they are not incentivised, they are not motivated, their hours have been cut, their number has been cut by half over the last 20 years, the equipment is not renewed.”

Reskilling dinner ladies is an essential part of the campaign: 70 have been retrained in Greenwich to cook again after years of just reheating food.

Along with “a proper meal on every kid’s plate”, the Feed Me Better campaign is demanding more funding for school meals (slogan: “Half a Quid a Kid”), better food education and the re-establishment of nutritional guidelines for school meals.

Last week’s announcement by the Education Secretary, Ruth Kelly, of new minimum health requirements are “a step in the right direction”, says Oliver. “It’s great that the Government is finally taking the issue seriously,” he adds. “But it’s a huge task and will need proper money. We need to invest in our kids and our dinner ladies.” The standards so rigorously applied to everything else that goes on in schools seem to fly out of the window when the bell goes for lunch, he says.

“One thing I have been really impressed by is the attitude of, ‘We know best, we are going to teach you and get you to try things’. The kids are in this learning environment, but then at lunchtime it’s all forgotten.”

Kidbrooke, once the beacon for a new way of education, is again leading the way. “It has transformed the place,” says Nora Banks. “There’s a stubborn streak in everybody and at first I didn’t think we could do it. But now we have, we’d never go back.”

Jamie’s School Dinners starts on Channel 4 at 9pm on February 23. More details on the Feed Me Better campaign at www.feedmebetter.com