It is lunchtime at Richard Challoner school, a Catholic comprehensive for boys in New Malden, south-west London. The familiar smell of school lunch is beginning to waft around the corridors.

In the canteen, there is a moment of calm as the kitchen team make final preparations before year 7 descend – a mass of chatting, laughing boys, with backpacks swinging and empty tummies grumbling.

It all happens so fast. One minute there’s an orderly queue, the next they’ve made their selection, completed payment and are sitting down – huddled with friends – to eat. The food vanishes and they’re off.

In comes the next sitting. Bigger boys with bigger appetites. Wednesday’s menu includes a main meal of sausages (Cumberland pork and Glamorgan vegetarian) plus mashed potato, with caramelised onion gravy, roasted carrots and broccoli.

There’s also a pasta dish, chicken meatballs in tomato sauce and jacket potato with baked beans. The “grab and go” offer includes sausage baps, pepperoni panini, cheeseburger and sweet chilli hash brown. There’s no deep fried food, no chocolate bars, crisps or fizzy drinks. There is however a well-stocked salad bar.

Dessert remains on the menu though – there’s a luscious display of chocolate mousse, banoffee pie, caramelised banana cake, brownie, marshmallow sponge, summer berry flapjack, iced rolls, cupcakes and double chocolate muffins. Would Henry Dimbleby and Bridget Phillipson approve? Maybe not, but they look delicious.

Earlier this week, the education secretary revealed plans to overhaul school food standards, as part of efforts to lower rates of childhood obesity. Welcomed by chefs and campaigners including Jamie Oliver, Emma Thompson and Dimbleby, a former government food tsar, the plan is to cut out food and drinks high in fat, salt and sugar and replace them with more fruit, vegetables and wholegrains.

Schools will no longer be able to offer “grab and go” options like sausage rolls and pizza every day and deep fried food will be banned completely. Sugar-laden cakes and puddings are also under threat, with fruit served for the majority of the week instead.

Headmaster Sean Maher bristles slightly as I outline some of the government’s proposals, now subject to a nine-week consultation. “I find that so nanny state-ish. Of course it’s our job to provide our students with as healthy and nutritious an offer as we can. But to say to a 12-year-old, ‘I’m not going to let you have a chocolate brownie after your lovely main meal’ … I mean, come on!

“You put healthy food in front of them, but you’ve also got to let them have play time. Surely they are allowed a little treat as well? And these guys,” – he gestures to the kitchen staff –“have also got to make money. You’ve got to be sensible about it.”

Until recently the school had been doing its own catering, but costs went up and the school went out to tender. Now they use a catering firm called Accent. The head chef Daniel Roche loves his job, he starts at 6am every morning, but says it’s hard making the sums add up.

“I love the kitchen,” he says. “I love the banter of the staff and – hopefully – seeing [the pupils’] happy faces. But if I was to stop everything tomorrow and only put healthy food out, we would be crippled as a business.”

The year 7s, in their first year at Richard Challoner, are still enjoying the choice the secondary school’s canteen gives them. Daniel, 12, is nibbling pizza, followed by flapjack. “I wouldn’t say they’re the healthiest, but they are really good.”

What if pizza disappeared off the menu as part of the DfE cull? “No pizza?” Daniel reflects for a moment as he continues to munch through his slice. “I would be a bit disappointed … but there are lots of other good things.”

Theo, also 12, sitting nearby, has opted for sausage and mash with extra salad, followed by a chocolate cup cake. He feels the government cutting back on sugar and cake is “a bit unfair. A bit harsh”. But, he adds, “I like the fact they are trying to make it healthier.”

Trivin, 11, is eating a burger, alongside Ollie, 12, who has a ham sandwich on white bread, with a cup cake. “I like the cheeseburgers a lot,” says Trivin, between mouthfuls. “They’re my favourite.” He also likes cucumber and sweetcorn. Carrots are too hard and tomatoes too squishy. Ketchup is delicious.

Trivin thinks his school “would go bankrupt” if they dropped cheeseburgers, cakes and pizza. “The entire place! I think people would get angry about that.”

Fraser, 16, brandishing two pieces of pizza, would be “a bit gutted” if it went off the menu. He doesn’t like brussels sprouts, he’s not big on broccoli, but he does like a sausage roll.

Ethan, 15, says the food at school is tasty and healthy but the portion sizes are too small. He thinks they should be allowed a sweet treat every day. “The sugars give you short term energy to get through the rest of the day.”

“It’s good food,” says Romelle, 16. “It’s nutritious food. It meets the needs.” He would like more vegetarian options, but he thinks cutting out dessert would make the meals dull. “Sweet treats bring a bit of excitement – especially in the lower years. It’s about keeping a balance.”