How did food in this country go so wrong? In the 1930s, Dr Innes Pearce's "Peckham Experiment" showed conclusively that when she and her colleagues educated working-class people in the basic concepts of nutrition and personal hygiene, it led directly to a significant improvement in social indicators such as health, marital stability, domestic income and educational achievement. In 1942, the Beveridge Report projected that the cost of running the National Health Service would decrease during the 1950s - the impact of a healthy postwar diet and better hygiene were expected to bring about huge improvements in public health.
By now we could - and should - be brimming with robust good health, eating a superb diet of healthy foods, rich in wholegrains and vegetables, and no one should be suffering from nutritional deficiency due to poverty. Instead, we have a situation where the poorest are also the fattest and where, increasingly, the onset of diet-related diseases such as obesity, diabetes and heart disease occurs in children, who can hardly be blamed for the consequences of the food they eat.
In 1946, Pearce and Lady Eve Balfour founded the Soil Association in response to the belief among doctors, scientists, farmers and nutritionists that postwar Britain could feed itself on healthy foods produced on healthy soils. But lobbyists for ICI and the chemical industry argued for subsidies on chemical fertilisers to encourage farmers to increase production. The 1947 Agriculture Act, in allowing them to do that, came down on the side of maximising production. The result was the centralisation of food production which brought about the concentration of power in the processing industries and, subsequently, in the retail sector. A true market, diverse and responsive to local demand, was replaced by a food chain of oligarchies. Small farms were vacuumed up into mega-farms and the farmhouses were sold off as country retreats.
Subsidised rapeseed in the EU and soya beans in the US drove natural hard fats such as butter, lard and palm oil off the market to be replaced with the cheaper, hydrogenated rape and soya alternatives. To make matters worse, in the 1980s and 1990s the NHS urged Britons to switch from natural fats to margarines, even though they were full of trans fats, which are formed when manufacturers hydrogenate fats and oils.Walter Willett, of the Harvard School of Public Health, called the hydrogenation of oils the "biggest food-processing disaster in history". According to Willett, for every 2 per cent increase in trans-fat consumption, a woman's risk of heart disease increases by 93 per cent. In Britain, trans fats still represent one-third of the average fat intake, itself 30 per cent of the overall diet.
Why did government policy go for cheap food as opposed to cheap clothes, cars or holidays - luxuries that exceed expenditure on food in the modern domestic budget? Who gained from such a budget? The direct beneficiaries were the oil and chemical industries, on whom industrial agriculture depended for their nitrates and pesticides. Indirect beneficiaries have been the medical and pharmaceutical industries, which have flourished on the back of the degeneration in public health.
In the late 1960s and early 1970s, my brother and I built a flourishing business by supplying some of the poorest members of society with healthy food. Our Ceres Grain Shop on the Portobello Road sold sacks of organic brown rice, wholewheat flour, grains and beans. And despite keen competition from the street market, we sold large amounts of organic vegetables. Healthy eating was not a class issue. Nor was it a problem that stemmed from low income. It is, and remains, a question of attitude.
In 1974, when my daughter came home from school requesting white bread sandwiches, to be like the other children, we gave them to her. Three days later she'd had enough and begged for wholewheat bread again. When the pupils from St Peter's Primary School in Nottinghamshire - where the original dinner lady Jeanette Orrey is catering manager - went on to junior school, they flatly refused to eat the appalling food. "We don't eat that stuff," they announced. Well-trained taste buds stay with you for life.
At the first Glastonbury Festival, brown rice-eating hippies barred the entrance to hot dog vans. They saw healthy eating as part of the alternative lifestyle and society they hoped to see emerge into the mainstream. They read John Seymour's Complete Book of Self Sufficiency, scraped together the money for a farm in the Welsh hills, then settled down to dreary factory jobs to make ends meet - until the market for their organic carrots suddenly took off in the early 1990s. As the healthy movement entered the mainstream, they felt they were losing control to the "big boys", and my brother and I saw our commercial monopoly on brown rice broken by the big white-rice packers as soon as it became big enough to be interesting. But with organic chocolate we somehow managed to steer a brand - Green and Black's - to category dominance before selling to Cadbury Schweppes.
When Stonyfield Farm Yoghurt, a hippie brand in the US, reached $200m turnover, it was bought by Danone, a French multinational. Frank Riboud, the chief executive, told the Wall Street Journal: "Stonyfield is more than just a balance sheet. Stonyfield represents an ethic and it's an ethic that we at Groupe Danone have to adopt if we're going to be successful in the 21st century."
You don't need a weatherman to tell you which way the wind is blowing in the corporate boardrooms. David Croft, who developed the Co-op's Fairtrade range, is now in charge of ethical sourcing at Cadbury Schweppes, while Nestle's wholegrain.co.uk website outdoes the Food Standards Agency in extolling the virtues of brown rice, wholemeal bread and pasta.
This trend will continue and, with luck, trans fats will become a historical anomaly. The health benefits of this single change are inestimable. It will fuel the rush to quality as manufacturers return to more traditional ways of processing food without the crutch of what is, essentially, a plastic made from vegetable oils instead of petroleum. Good food and healthy eating are now firmly in the mainstream. The principles and ingredients of a healthy diet that were derided in the 1970s are now the subject of glossy food magazines and rivetting TV programmes.
The Soil Association's Food for Life campaign supports dozens of local authorities determined to rectify the error of prioritising cheap food in school meals. Children can visit organic farms to see where food comes from and understand the issues that organic producers espouse with such passion. Vegetable box schemes, the refocus on local, often organic, food production and the renaissance of cookery are restoring good food to its rightful position in our culture. The repercussions will ripple through our entire value system and affect the way we think about ourselves and the world we live in. A crass nutritional materialism has left us with a generation whose health problems will be a burden on their ageing parents and on their own children. The social cost of a misguided cheap food policy has been enormous. The postwar vision of good food and health for all may have turned sour, but the dream has been revived and Britain is on the path to a food culture that combines the best of tradition with a deeper and more widespread understanding of good nutrition.
Craig Sams is chair of the Soil Association, founder of Green & Black's and author of The Little Food Book