In 1908, at tables laid with fresh cloths, more than 3,000 of the poorest school children of Bradford sat down to eat a two-course lunch every weekday. In the centre of each table was a vase of flowers. These were the ideas of Ralph Crowley, a pioneering medical officer in Bradford who first helped revolutionise school food in the UK.

Often, it feels as if we have made no progress in a century. On hearing that Theresa May was planning to “save” £650m by scrapping free school lunches for infants and replacing them with cheaper breakfasts, my first thought was: what would Crowley say? But since he died in 1953, I waited instead for Jamie Oliver’s response. A tearful Jamie gave an interview to Channel 4 attacking the proposal as “short-sighted” and “awful”. He pointed out that the short-term savings of scrapping the free lunches would be eclipsed by the long-term costs to the public purse of childhood obesity and type 2 diabetes caused by bad diets.

Jamie’s right. It’s shocking that just 12 years after he (and other campaigners such as dinner lady Jeanette Orrey) worked to secure new healthy school food standards in Britain, the value of decent school lunches should once again be questioned. Wholesome school lunches may not be enough by themselves to transform the health of a child who subsists on chips and sugary pop the rest of the time, but nor are they insignificant. Around 900,000 children from struggling families are set to lose their lunch entitlement when the free meals are repealed.

In a Britain where only 16% of children eat the recommended five-a-day of vegetables and fruit, free school lunches are a sound investment in national health. Some say universal free meals are a superfluous luxury for the middle classes, but all children benefit when the whole school is invested in the canteen, not least because school kitchens need a certain level of take-up just to break even.

Some things are worth spending money on. At my own children’s primary school, I’ve watched the free school meals for infants transform the way that children relate to eating in those early years. When everyone eats the same lunches, teachers have told me that it’s easier to teach lessons on healthy eating, because everyone has access to the same ingredients. For my youngest (aged 8) and his friends, school lunches have become a (mostly) lovely shared experience, as collective a part of the day as assembly.

When my two teenagers were at primary, by contrast, the school meals service was something that most families dipped in and out of, leaving only the poorest stuck with and stigmatised by their hot lunches.

Subsidising lunch for all families is not very “sensible” says the Tory manifesto, as if feeding children were simply throwing gold into so many thankless mouths. But school lunch at its best is not just about satisfying hunger – crucial as that is. It’s about having time to sit with your friends and share something. It’s about discovering that maybe fish pie is not so scary, but might be delicious because the cook served it to you with such a kind smile. It’s about basic wellbeing, that thing we talk about so much and enjoy so little.

School breakfasts can serve many of these functions too – as the excellent work of the charity Magic Breakfast confirms – but most children don’t arrive at school early enough to benefit from them. The proposal for universal free school breakfasts feels like a cynical move deliberately designed so that the fewest people will take it up.

The voice I wish we could hear now is that of Ralph Crowley. He would have said that we should not be talking about school breakfasts or school lunches, but both. The whole point of school meals is to ensure that every child has the nutrition needed to learn across the whole day. In contrast to May, Crowley saw the midday meal as the most important – the best chance to give a child protein and vegetables. But he also insisted that children who arrived hungry in the morning should be given filling breakfasts of porridge, milk or cocoa and “wholemeal currant loaf” before the first lessons.

Thanks to Crowley, Bradford schools once had meals that were famous in educational circles throughout the world. As in other British cities, teachers in Bradford had been horrified at the large number of children arriving at school too hungry to learn (another problem that, scandalously, has not gone away). After the School Meals Act of 1906, Local Authorities had the power to serve free school meals for the first time. Nowhere took up the challenge with more enthusiasm than Bradford under Crowley. More than 100 years ago, he saw that school meals not only supported a child’s learning but were a form of education in themselves, hence his insistence on tablecloths and flowers. School meals, he saw, were a chance for children to learn new tastes and social skills.

Benefits like these might be difficult to measure but they are certainly vital. To treat school lunches as a wasteful trifle shows we are the ones who need educating in what food really means.

• Bee Wilson is a food journalist and author. Her latest book is First Bite: How We Learn to Eat, published by Basic Books and Fourth Estate