It is lunchtime at St Winefride’s Roman Catholic Primary and the dinner hall is heaving. The queue for food is bustling and in constant flux as eager youngsters run to the front to eye up today’s offering and try to jump ahead.

Roast lamb seems to be the most popular choice today, along with the sweetcorn, but no matter what’s on their plate, every tray has a piece of melon or a selection of summer berries. The doors open on to the playground, where younger pupils have had their fill and are playing with hula hoops, competing to see who can keep theirs spinning the longest.

St Winefride’s is in the borough of Newham, east London, one of three local authorities in the country taking part in a Government-funded pilot scheme to provide free school meals for every primary pupil, not just those who qualify on income grounds. As well as tackling obesity and improving children’s health and eating habits, the scheme also aims to bring benefits in behaviour and academic performance.

The take-up at St Winefride’s has been dramatic. Almost all - 98 per cent - of its 300 pupils are opting for a hot meal at lunchtime, compared with 27 per cent previously. This has been mirrored across the rest of the borough, where up to 75 per cent of children are taking part.

As areas of high deprivation where the intended impact could be felt most, Newham, Durham and Wolverhampton were chosen to participate in the pilot. Newham has the second-highest obesity rate in the country for Year 6 pupils and the third highest for reception children.

On top of this, 52 per cent of children in the borough experience childhood poverty - defined as less than 60 per cent of the median UK household income, which is currently pound;407 per week.

Munachim, a self-confessed junk-food lover, now eats lunch at school every day. “Before, I would eat cake, chocolate, and sometimes take away chips for lunch. I didn’t eat my sandwiches, and I’d be asking my parents for unhealthy food,” he says. Now he enjoys cooked lunches and has more energy during the school day. “My dad thinks it is really good, too - he saves lots of money,” adds the 11-year-old.

The impact of the pilot programme is being monitored over two years, but Paul Underwood, headteacher at St Winefride’s, is already convinced of its value.

“I was always surprised at our school because the children on free school meals did better than many of the others,” he says. “It is supposed to be the other way around, but the children who brought in packed lunches didn’t do so well, academically and in terms of behaviour.”

The previous Labour government had planned to widen free school meals provision to a further 500,000 children from this September, and to extend the pilot scheme to another five local authorities: Bradford, Nottingham, Cumbria, Medway in Kent and the London borough of Islington. But Education Secretary Michael Gove shelved both plans earlier this year on cost grounds, although the existing pilots were allowed to continue until their original end date next July.

At St Winefride’s, the number of pupils eligible for free school meals was lower than in many other Newham schools - 10 per cent, compared with a borough average of 50 per cent. But making the meals free for all has had a noticeable effect in the classroom, says Mr Underwood.

“We can teach English and maths in the afternoon now, as the children can actually concentrate after lunch,” he says. “They feel better in themselves, and you can tell.”

Since a nutritional standard was introduced by the School Food Trust in 2008, a school lunch is required to provide children with essential vitamins and nutrients. Packed lunches, by contrast, are more likely to be filled with junk food.

The impact of healthy food has been so great that the school has set up a breakfast club at a daily cost of pound;1 for every pupil.

For the past few years, the school provided breakfast for Year 6 pupils during the week of their Sats exams to make sure they had a good start to the day and were calm and settled in the morning.

Sometimes Victoria, 11, does not have time to make breakfast for herself. Her mother works long hours and it is usually her sister who cooks dinner. “Before we got free school meals, I made (lunch) myself, but I’d usually have chocolate,” she says with a cheeky grin. During Sats week, when she was having breakfast and lunch at school, Victoria’s mother noticed that her daughter was more alert and less irritable.

While most families of pupils at St Winefride’s would not qualify for free school meals under the previous system, many are in low-income jobs and the cost of paying for a school dinner could be a significant disincentive.

“They’re very caring parents, but a busy lifestyle means they don’t have enough time to prepare healthy meals,” says Mr Underwood. “Lots of them are nurses or cleaners. They might have to be at work at half seven in the morning.”

Although Government funding for the scheme will finish at the end of this academic year, the local authority has been so impressed by the results so far that it has pledged to keep it going. As well as matching the pound;2 million from central government, the authority has also found pound;1.6 million to cope with the higher-than-expected demand for school meals.

The council’s cabinet member for children and young people, Quintin Peppiatt, says he is convinced that the scheme will end up paying for itself. “The levels of obesity and malnutrition are in the top ten for the country,” he says. “Some of the problems in the home are linked to poor health, and providing universal free school meals should help with that, putting less pressure on the health services.”

Universal free school meals are also more cost-efficient for schools, coming out 10 per cent cheaper to run than the previous system due to reduced administration costs, according to Mr Peppiatt. “It has also put 180 local people into work and they have the opportunity to train and get further qualifications,” he says.

Providing primary children with free school meals does not change children’s attitudes to food overnight, if the 10-strong pupil council at St Winefride’s is anything to go by - all of the children, aged from six to 11, admit to eating and loving take-away chicken and chips several times a week.

All the children on St Winefride’s pupil council have at least one parent who works in the evenings, so a home-cooked meal is a special occasion.

“When my mum is not well, we have sausages,” says eight-year-old Rajeevi. “But if my mum is well, we have curry and rice.”

But as far as these pupil representatives are concerned, the free school meals pilot is a success. “Everyone’s looking forward to lunch now,” says Munachim.

For Rajeevi, the most important thing is not that the meals are tasty or that they meet a nutritional standard, but that they are there. “I love having school meals,” she says. “Afterwards, I feel full.”