What we eat is what we talk about. Red meat v. non-red, all meat v. no meat at all, GM v. organic, long haul v. local, dirty v. ‘environmental’ and so on; how we prepare a dish, how Heston Blumenthal does it. What makes these conversations possible is the abundance we’re now accustomed to: plenty is the medium in which our anxieties, our pleasures and even our ‘ethics’ thrive. So it comes as a bigger shock than the salmonella scare (Edwina Currie, 1988) or the BSE scare (John Selwyn Gummer, 1990) to hear the latest strand in the table talk: that the era of endless food is winding down.

This belief is new. Until recently the discussion was largely about quality. Quantity and availability only entered the picture when we wondered how to reconcile the diet of a British family with that of a poor family in east Asia, say, or the Horn of Africa. The answer used to be simple: free up the markets, oppose trade barriers for producers in the developing world, extend bilateral aid to their countries, but be sure to eat up, because the more we put away, the better off the struggling poor will be. In the newer thinking, however, our habits are dangerous for them, but also for us: we are eating beyond our means and stretching our supply lines. A food supply that depends on imports (90 per cent of the fruit we consume, 60 per cent of the vegetables) is vulnerable: food policy experts were advancing this view well before the eruption of Eyjafjallajökull. VFC – ‘Volcano Flight Chaos’, as the BBC referred to it – was no more than a beginner’s level test of food security. Most of our food imports come from the EU, by truck and ferry; bananas still arrive on the banana boat. Had the flight ban continued, exporters in developing countries would have taken critical losses: three days into the shutdown, Blue Skies, a fair-trade supplier, posted an SOS to the effect that its processing factories in Latin America and Africa were closing. Exporters of perishable food from Britain would have suffered too. Consumers would have noticed gaps on the exotic fruit shelves, but we’d have remained well short of a level-red threat to the food supply.

The threat is there, however, as the food prophets have been warning us. ‘The appearance of infinite abundance is an illusion’ (Tristram Stuart, Waste, 2009). Habits ‘will have to change if only because they simply cannot go on. We are now entering a period of rapid transition’ (Felicity Lawrence, Eat Your Heart Out, 2008). ‘We depend just as much on our gas-guzzling, chilled plug-in, “just-in-time” food deliveries as ancient Romans did on foreign conquests, shipping and slaves – and our food system is no more secure, ethical or sustainable than Rome’s was’ (Carolyn Steel, Hungry City, 2008).

These opinions are shared by many organisations in the UK, among them the National Farmers’ Union, the Soil Association, the Sustainable Development Commission (a government watchdog) and even the Royal Institute of International Affairs. They underlie the ‘Food 2030’ strategy launched by the Department for Environment, Food and Rural Affairs in January: ‘Our food system needs to be prepared for shocks and to be able to manage risks – from climate change, sharp commodity price increases and natural disasters to food contamination.’ At the production end of the British system farming capacity must be shored up. At the retail end, there is concern about the future of imported produce. The effects of water shortage and climate change get ‘critical’, a senior manager of Asda told me, ‘round about 2030 to 2050’. His suppliers of fruit and veg are already relocating from Spain – they’ve depleted the aquifers of the south-east coast – to Morocco, where there is enough ground water to last them until 2035.

Defra’s is the latest warning that sooner or later rises in temperature, water shortages, crop failure, diversion of grain yields to livestock and biofuels, disease in the animals we’re eating, soaring energy costs and armed conflict will disrupt the delivery systems, built on long distances and short order times, that service our needs. The new hesitation about food reflects broader doubts about the last 30 years – the trente glorieuses of the Anglo-Saxon model: our confidence in the energetic binge-and-treadmill culture that propelled us through the 1980s and 1990s has taken a knock. We doubt, above all, whether we can pay off our rising debts to the environment. Feelings about eating and not eating are more immediate than thoughts about rainforests; like the energy or water embedded in the produce we buy, many fears, including fundamental ones about life and death, destruction and incorporation, are already embedded in food. Others migrate to it, making food the bearer of unwieldy questions about the survival of a planet whose destiny we can’t foresee and the fate of people whose problems aren’t the same as ours. Do we bolt down what’s in front of us or do we curb our appetite in the name of our children’s future, or a ‘good’ we can’t guarantee? The modern table is groaning with dilemmas.

They’ve been compounded by global price increases – and the trends that policy analysts and scientists believe they reflect. Since 2000, worldwide cereal harvests (wheat, maize, rice) have outstripped anything in the 1990s, yet between 2005 and 2008 prices soared: wheat and maize grown in the US rose by about 130 per cent; so did American soya, which goes mostly to animal feed. Dairy prices shot up (butter by 74 per cent, powdered milk by 69 per cent); the price of chicken went up by two-thirds. A month before the banking meltdown in 2008, ‘food inflation’ was running at 12.8 per cent in the UK. The hit was manageable in Britain, where on average we spend about a tenth of our income on food – in developing countries, it can be seven times that amount – but it was still a hit. There were short-term reasons for these rises: global grain stocks were low, the weather had been hard on farmers, grain-producers withheld exports, there was pig disease in China and bluetongue in the EU. In 2009 price inflation eased off but food experts were already saying we shouldn’t rule out a similar crisis before long.

Last year, a team of experts and strategic analysts recruited by Chatham House published their findings on ‘food futures’ and the looming threats that we should keep in mind. As one of them explained to me, food is now a ‘real security issue’, too long obscured by the government’s preoccupation with ‘terrorism and razor wire’. Their study identifies seven factors, or ‘fundamentals’, bearing down on the global food supply – of which Britain’s is a small part.

The first is the nature and extent of population growth: we are six billion now and by 2030 we’ll be eight billion; increasingly we are clustering together and most of us are now living in cities, which is also where most newcomers will be born. Urbanisation on this scale poses big questions about land use (housing v. farming) and the production of food by a minority for a majority as the gap between the two gets wider.

The second is ‘the nutrition transition’: generations that once lived on grains, pulses and legumes have been replaced by more prosperous people with a taste for meat and dairy. Crops like maize which once fed many of us directly now feed fewer of us indirectly, via a costly diversion from which they emerge in the value-added form of meat. Global production of food – all food – will have to increase by 50 per cent over the next 20 years to cater for two billion extra people and cope with the rising demand for meat.

The third factor is energy: the industrial production of food is sure to become more expensive as fuel costs rise. It takes 160 litres of oil to produce a tonne of maize in the US; natural gas accounts for at least three-quarters of the cost of making nitrogen fertiliser; freight, too, depends on fuel.

Land is the fourth. The amount of the world’s land given over to agriculture continues to grow (in the UK, roughly 70 per cent of land is agricultural), but in per capita terms it’s shrinking. As with oil, it’s possible to envisage ‘peak food’ (the point of maximum production, followed by decline), ‘peak phosphorus’, i.e. the high point in the use of phosphate fertiliser (one estimate puts it at 2035), and, as the FAO suggests in its diplomatic way, ‘peak land’: the point at which the total area of the world’s most productive land begins to diminish (soil exhaustion, climate change) and marginal land comes up for reassessment.

Alternative fuels are reducing the amount of land available for growing food. When the Chatham House team began its work, the first effects of the rush for biofuels were becoming clear. In 2006-7, about 30 million tonnes of grain were diverted to bioethanol. That’s less than 5 per cent of global wheat and maize yields, yet the World Bank felt it was instrumental in driving up food prices: many wheat exporters, including EU countries, had turned their land over to biofuel crops, with the result that by 2007, global wheat stocks were half what they’d been at the turn of the century. The biofuels industry is squeezing our capacity to feed ourselves.

Worldwide, one in three people face water shortages – factor five – and by 2030 the ratio will have narrowed. Why should a global water shortage put pressure on the UK, with its high rainfall? Much of our fruit and veg comes from water-scarce countries and as Sir John Beddington, the government’s chief scientific adviser, remarked last year, lack of water closes down food production and livelihoods: from the European edge of the Mediterranean to points east and south, it will turn migrant workers and settled communities into drifters and foragers. Places like Britain with sturdy, rain-fed agriculture must stand by to grow a lot more and face the prospect of inward migration. Any surplus food will be welcomed elsewhere, including in southern Europe, where water gets scarcer by the year.

A sixth factor is climate change and its downward pressure on cultivation in many parts of the world; extreme weather events will also jeopardise agriculture and the movement of food from one place to another.

Finally, there is the state of the world’s 1.1 billion agricultural workers: more than half of them own neither land nor machinery and live in a state of semi-slavery. The conditions of this new global underclass are at last a matter of concern: worldwide food production is set on a downturn as their wretchedness weakens their capacity to produce and earn, driving more people inexorably towards the cities. The head count of these land armies – 600 million at a guess – sounds impressive but it doesn’t change the fact that the overall number of people working in agriculture is falling. ‘In both developed and developing countries,’ the Chatham House report states, ‘the pressure on the agricultural workforce is increasing.’

Land and labour issues are present in Britain in a low-key way. Take the tension between immigration policy and the need for foreign workers: government capped the number of migrant fruit-pickers at 16,000 in 2007; the strawberry growers and the NFU lobbied hard to raise the cap – this year it’s 21,500. The average age of the British farmer is higher by about 20 years – some put it at 58 – than that of the worker in the Square Mile. Farming is no longer a career in demand. Tax relief for farm properties has led to the rise of speculation in farmland, while tenant farming has fallen away. Farming incomes rose last year, as they did in 2007, but unless you’re a barley baron with a vast acreage in East Anglia, the going is tough. The average income of a full-time farmer in the early 1980s – £26,000 in today’s prices – has fallen by about £10,000. Three years ago, a Farmers’ Voice survey found that one-third of the 2000 farmers it approached were worried about staying in the industry or meant to get out altogether. Increasingly, farmers supplement their income by ‘diversifying’ into bed-and-breakfast, farm tourism, go-kart tracks … Anything to weather the low points – BSE, foot-and-mouth – and survive in the narrow gap between rising input costs (fuel and fertiliser) and dwindling receipts: between 1998 and 2008 the farmers’ share of the price their food fetches at the supermarket checkout fell by 22 per cent.

Scientists, policy analysts, nutritionists, campaigners – call them the food observatory – don’t have seven big solutions to the seven fundamentals. Instead, they put together a mix of different approaches, shuttling strategically between agricultural and cultural, global and parochial, chemical and organic, the death of the planet and the fun of the kitchen, ‘sustainable production’ and ‘sustainable diet’. You only have to spend a moment on the literature to grasp that these are not confused people, unable to make up their minds; it’s simply that they want a range of interventions on several, overlapping fronts, and soon. So at one level, consumers must be urged to change their habits. At another, retailers must encourage consumers to make that change. At another still, government must repair the heavy machinery of policy, which has been left to rust when it might have helped consumers, chivvied retailers into line and revived British farming.

The food observatory is looking for a new kind of consumer, whose habits are informed by the seven big stories and who acts – or eats – accordingly. Climate-change consciousness plays a big role in this. What better place to think about the environment than at the table? Yet there’s a magical quality in the way the part has come to stand for the whole: we are now hoping to influence very large outcomes, well beyond an individual’s control or even that of a single society, by transforming matter and placing it in our mouths. This mixture of the down to earth and the sacramental is very powerful and it’s one of the reasons we’re seeing more rapid developments in our attitudes to diet than in our dawdling contemplation of climate change itself.

Cue the role for government. Broad agreement about the precarious future of food in the UK is a more attractive prompt for anyone in Westminster than melting polar ice, and politicians clearly feel there’s a point in trying to protect Britain from a breakdown in food supply (a far more remote possibility in France and the US, where old statist habits persist). Defra believes it’s time to arrest the decline of farming capacity. It wants more young people to consider farming as a livelihood and landowners to lease to people who’d like to grow food. Four months before the election campaign, Hilary Benn announced a modest £50 million funding top-up for food and farming R&D over the next five years. In Food 2030, Defra insists that Britain must find a way to farm and fish ‘sustainably’ – that word again – setting out targets and measurements (monitoring soil quality, water use, greenhouse gas emissions, fish stocks etc).

The trouble is there’s very little money in the pot. That’s why Defra puts such stress on tending the shoots of the cultural revolution it has identified. In the rise of the celebrity chef, the national appetite for appetite, the prowess of the kitchen, the pride of the vegetable plot, the bustling farmers’ markets, the government sees how aware we’ve become about food. Defra reported last year that one-third of Britons already grow some of their fruit and vegetables – generally thought to be an encouraging sign.

At the same time Defra has taken the opportunity to talk openly about the worrying thoughts in our heads as we drain the brown fluid from the meat in a polystyrene punnet. Obesity, heart disease, animal welfare, greenhouse gases, the nagging intimation that we can’t go on as we have without parts of the food chain shearing away: Defra grasps that our misgivings, like our pleasures, could lead us towards a serious re-evaluation of food without massive expense to the public purse.

At the outbreak of the Second World War, the last time a British administration felt that the entire food supply was in danger, government had a decisive role. Nowadays it can spell out desirable objectives, but it is only one member in a partnership with producers, retailers and consumers. The consumer is still the child-sorcerer of market democracy, sweet-toothed and capricious, gaining weight by the meal and ready to throw it about: government can’t quite face off against us. Well, not yet – but there’s a strong hint that in Defra’s thinking ‘choice’ is no longer the only yardstick of the democratic mile. It prefers ‘informed choice’, but who will inform us? While government will be pressing retailers to get into line, with more sustainable, healthy offerings on the shelves, campaigners who’ve been lobbying Westminster for change will needle away at us in more outspoken terms than politicians can afford to use. Politicians will tell us what we’re doing right while campaigners of one kind or another – including the press – will tell us where we’re going wrong, in schools and in ‘the community’.

For Defra’s ideas to come good, it won’t be enough for one-third of the population to tend radishes in their window boxes. There have to be producers turning out several tonnes of food a day with the seven big stories in mind. Modern hydroponic schemes are well established in California and the Netherlands and for British growers a state-of-the-art version now exists on the Isle of Thanet.

A consortium of Dutch growers and Fresca, a fresh-produce agglomerate whose food has been through millions of gullets in Britain, first explored the possibility of massive, hydroponic, low-carbon horticulture in Britain six years ago. Lloyds agreed a loan for part of the infrastructure, but no UK bank would put up anything like the money they needed to create Thanet Earth, billed as the largest glasshouse complex in the UK: British banks simply didn’t get it. In the end, Rabobank in the Netherlands underwrote Thanet Earth.

Fresca and the growers bought up 90 hectares of land and began assembling their gigantic rectangular hangars: there are now three gleaming glasshouses covering roughly a quarter of the site. In aerial photos they look like giant solar panels; from the road, as you approach, like blocks of polished quartz. Lagoons have been dug to capture rainwater. In the glasshouses themselves, peppers, cucumbers and tomatoes are grown; in the tomato greenhouse growth is driven along through the winter by stadium lighting. In 2009, Thanet Earth’s first year in production, 2.5 million tomatoes left the glasshouses for the sorting area in an average week; the cucumber and pepper harvests peaked at half a million and three-quarters of a million a week. The company reckoned it was meeting 2 per cent of UK demand. Planning permission exists for another four glasshouses on the site and the target, at that point, is to supply 4 per cent of all tomatoes, cucumbers and peppers consumed in the UK.

In the tomato glasshouse, the sharp, sage-and-lime scent of the vines is the strongest impression. The next is that there are very few indigenous British among the workforce running trolleys up and down the rails built into the grid layout of the building. ‘They’re originally Eastern European,’ one of the Dutch growers explained. ‘Only they’re in Thanet for the long term and they’re not thinking of going back.’ They are not strictly ‘migrant’ labour, but they’re waged and, at present, non-unionised. So on one of the seven fundamentals – the precarious lives led by the people who feed us – Thanet Earth score no better or worse than any other grower.

On water they are ahead. Their produce is grown on blocks of rock wool about a metre off the ground; surplus water drains into long trays underneath the blocks and from there it’s borne off to the lagoons, along with rainwater off the roofs, to be pumped around again. The company’s energy strategy is imaginatively back-to-front: first build a substation to power the entire complex and bathe your plants in light; sell your surplus to the national grid, capture the waste heat from generation and divert it to the produce. The glasshouses are heated by emissions from the generating process, which are run through kilometres of baggy tubing under the plants: every few minutes there is flatulent sigh as heat and CO2, on which growth depends, come gusting out of the tubes. This system, known as Combined Heat and Power, is not nearly as widespread in British horticulture as it might be. On other issues – minimal pesticide use, preserving the biodiversity of what was once a sprawling cauliflower patch on the Kent coast – Thanet Earth is a virtuous producer.

Thirty Thanet Earths could bring Britain to self-sufficiency in ‘salad’, but even if you regard that as a triumph, there are snags. For one thing, new glasshouses would have to be on or near the same latitude (approx 51 degrees north), as they are in Holland, to make the most of natural light. For another, buyers for the big UK supermarket chains can squeeze a mega-grower like Thanet Earth as hard as any other producer. A larger query hanging over hydroponic growing in the UK is quite what it solves until we all start eating many more tomatoes, cucumbers and peppers. This means we have to agree on what foods we ‘should’ be eating and which of those we’re short of in Britain.

The UK is about 60 per cent self-sufficient in food, yet food analysts would like an increase in domestic production, some arguing that a global shortage of food puts us under a moral obligation to grow more, others that it’s a big revenue opportunity for Britain. The next point they make is that the foods we have in abundance – meat and dairy – are the ones whose intake we need to moderate, while the foods we import – fruit and vegetables – are the ones we should learn to like: meat and dairy put far more strain on the health budget and the environment than fruit and veg do. Defra agrees with these dietary imperatives, but it won’t call the balance of imports and exports into question and thinks our £18 bn trade deficit in foodstuffs is about right. We have trade surpluses in other sectors: why wouldn’t the principle of comparative advantage hold good for food?

Shopping in the big Sainsbury’s near Ladbroke Grove, you’ll find fruit and vegetables cascading in from the EU, Mexico, Honduras, Costa Rica, Colombia, Brazil, Argentina, Chile, South Africa, Egypt, the Occupied Territories, Kenya. (In return we sell them booze, red meat and smoothies.) The presence of sustainable hydroponic culture in the UK could mark a radical upturn in domestic production and signal a change not only in what we eat but where it comes from. The new consensus among environmentalists, nutritionists and academics is that it has to.

In 1939, the figures for self-sufficiency were the other way about: Britons depended on two-thirds of their food coming from overseas, mostly possessions and dominions. A map drawn at the time, and reproduced in a memoir by Lord Woolton, minister of food during the war, as well as on this page, drove home the point that if two or three supply routes were cut, hunger and shortages at home were sure to follow. (Note the threat to jam.) Woolton’s department took charge of the supply and distribution system, effectively buying up food in Britain and selling it on to the population. Labour and resources were put at the disposal of British farmers and the order went out that everyone should dig for victory. Within four years Britain had doubled its domestic food supply. Food production peaked in the 1980s, since when it has dropped away.

Only hardliners believe in full self-sufficiency for Britain. Realistic food observers who argue that we should boost domestic supply tend not to use the term. They talk instead about the importance of ‘sustainability’ and ‘resilience’ – we’ll come to these – as the two prerequisites to ‘food security’, the objective they have in view. The FAO defines food security as a state of affairs in which all members of a given community ‘at all times, have access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life’. That’s a tall order even in developed countries: in the UK there could be as many as one in 12 people experiencing the opposite of food security, i.e. ‘food poverty’ (the figure was four million when the Rowntree Foundation looked into it ten years ago).

When food experts speak about ‘resilience’, they are expressing concern about the hair-trigger system of delivery in Britain. Supermarkets are the genii of the logistics game: barcodes going through the checkout enable a precision-picture of the state of the shelves in any given outlet and trip the switch for incoming orders, which arrive ‘just in time’: the process is so finely tuned that most of the warehousing a supermarket chain requires can be handled by a fleet of lorries plying our motorways round the clock. In the new thinking, this is cutting it fine, like only ever refilling the tank of your car with a couple of litres: it works as long as there’s nothing you hadn’t thought of, but it also means that Britain is never much further than ‘nine meals from anarchy’, as Andrew Simms, head of the New Economics Foundation, put it.

A sudden disruption, caused by extreme weather, or an energy crisis, would leave a government depending on the expertise of the supermarkets, currently servicing a Byzantine consumer choice model, to get food around the country. The just-in-time system would become a hardy distribution engine, patrolled by the police and maybe the army, while a break in the food chain was repaired: a source of weakness, in other words, becomes a strength in an emergency. But this still leaves analysts worrying about external shocks that could disrupt the complex networks and long supply chains – see Woolton’s map – along which fruit, vegetables, soya and fertilisers make their way, and wondering whether a community can arrive at resilience if it’s only as strong as the markets on which it depends. Defra, of course, stops short of this last reservation, but the Sustainable Development Commission insists that markets may look very different in future and we shouldn’t assume that our strong ‘financial and service sectors’ will enable us to access food from around the world indefinitely. Better to arrest the decline of British farming: the carnival of food awareness in the UK requires a corollary in the landscape of production.

The word ‘sustainability’ and its cognates occur more than 150 times in Food 2030. A ‘sustainable’ culture is one that produces and consumes within its means; if it functions with an eye to the sustainability of other communities, so much the better. In the academic literature, sustainability is now the bedrock on which food security is thought to rest.

The most passionate advocate of this view is Tim Lang, who began his radical contemplation of food during the 1970s, when he worked a hill farm in Lancashire. He’s now professor of food policy at City University. It was Lang who showed me Woolton’s map, with its premonition of food miles, a concept he himself developed in the 1990s, and when we met, he took me back to the repeal of the Corn Laws in the 1840s: a good example, he believes, of trading interests driving down domestic food production. Lang is not opposed to trade; it’s just that on the religion of the markets he is agnostic and feels this is becoming a respectable position: whatever they say in public, fewer people in government now think that ‘food security can be left to the market.’

An insight into food miles in 1940

Lang puts great weight on the seven fundamentals; he also has a longstanding interest in food ethics and what he calls its ‘underlying hardness’. What does that mean? People who worry over the rights and wrongs of the Kenyan mangetout or greenhouse gases embedded in meat seem, on the face of it, to have ‘fuzzy’ thoughts (Lang’s word), circumscribed by ‘niceness’, but equally they’re pondering the move away from a food system built on cheap, plentiful oil and fertiliser and abundant water, which may be tougher than we think. Such a move could breathe life into muffled conflicts about land and wealth and widen the perimeter of shortage beyond developing countries. Food ethics, Lang says, sees past ‘the core values of consumer capitalism: the “right” to unalloyed choice, purchaser power, the pursuit of lower prices, ignorance about the nature of production’. It isn’t really to do with niceness.

A common thread in the alternative food movement – stronger in Britain than in any other EU member state – is a rugged opposition to the ‘externalised’ costs of food. Like mainstream food prophets, Lang takes the view that what we eat in Britain is cheap because so many of the real costs of producing it are absent at the checkout. Costs, that is, in terms of underpaid labour in distant countries whose poverty becomes a burden on their communities, land exhaustion, motorways pummelled by ‘just-in-time’ deliveries, billowing carbon emissions, the conjuring of tropical forest into soya and from there into the British Sunday roast. A mass of debt is embedded in the way we produce and eat. One example: a study in 2000 put the price of cleaning up the UK water supply after a year of farm pollution at around £200 million – an expense that sidles past the till to hit the taxpayer or the utility customer later. You could just call that redistribution, but food campaigners don’t: they think there are too many hidden costs in food that get shrugged off to the environment, or dumped on the world’s poor.

If you agree that all countries must produce as much food as they can, then the Common Agricultural Policy is no longer the monster food campaigners took it to be. To Lang it is lumbering and anomalous, but still a useable legacy of the ‘productionist’ era, as he calls it, when prosperous states, and others – India, for example – revolutionising their agriculture, intervened in farming and markets to raise output. He regards it as a benign phase in the history of food policy, informed by the Great Depression and the Second World War. The 1947 Agriculture Act in Britain, which saw massive support for farmers in the form of price guarantees and marketing boards, corrected shrewdly for the end of Empire and was informed, as Lang has written, ‘by a moral duty to increase output and to ensure the adequacy of supplies for public health’.

Excess, waste, high chemical inputs, environmental damage, barriers against struggling growers in poor countries: Lang is alert to the horrors of the CAP, but he sees a strong case for reform and none for running the policy down. In a briefing paper last year – and you can hear Lang’s voice – the SDC called for ‘a new Common Food Sustainability Policy’ built on radical reform of this agro-funding powerhouse and the way in which food is grown; how fertiliser, pesticides and GM are used (Lang is opposed only to their ‘corporate hijack’), how land is managed and labour rewarded. The overriding point, he says, is that sustainable production must be increased everywhere: ‘Growing more here needn’t mean cutting off producers in the Third World, in my view.’

Lang has coined the expression ‘omni-standards’ to suggest a variety of approaches to the seven big stories. They might have to do with the prevention of obesity and diabetes, animal welfare, reforestation, fair prices for vegetable growers in Africa or dairy producers in Europe: every argument is carefully examined and the points at which they intersect are noted. In his tenacity and command of the materials Lang can strike you as a one-man wartime ministry of food. Even big retail management, some of whom regard him as a tricky customer, have begun to acknowledge his ideas.

‘Sustainable diets!’ he announced cheerfully, waving me down the steps at City. ‘For all this to work, the food on our plates is the thing … it’s the mediating idea.’ It put me in mind of Naked Lunch: ‘a frozen moment’, Burroughs said of the book’s title, ‘when everyone sees what is on the end of every fork’. In Lang’s frozen moment, we see the whole story as our food arrives on the table: the place where all the issues coalesce. Perhaps it’s another way of saying grace, though to Lang there’s no mystery in what we’re about to receive. It shapes lives and puts pressure on eco-systems in distant parts of the world as well as our own.

A few conversations with food observers and you’re starting to decode your surroundings for clues about sustainability. Driving up to the Glemhams in Suffolk last winter, I couldn’t pass a lorry without thinking there was a 25 per cent chance it was on a round-trip food delivery and a 50 per cent chance it was empty; couldn’t scan a field of winter wheat without wondering if it was destined for pigs or poultry; couldn’t imagine my way beyond the low, courteous country either side of the A12 to a vision of cattle ambling in the Stour Valley without totting up what it takes to produce a kilo of prime beef: 35 kilos in greenhouse gas emissions, eight to 15 kilos of grain, maybe 10,000 litres of water, depending who’s counting. Food experts are working hard to express those costs in pounds, dollars and euros, but who will agree on their sums? Would the bill take the form of large numbers of destitute people clamouring for space? Apparently, what we eat must now bear the burden of fears about population movement, as Beddington hinted last year in his remarks about water.

At her home in Great Glemham, Caroline Cranbrook recalled how she’d joined battle with the big retailers in East Suffolk in the 1990s on the grounds that out-of-town megastores drive high street shops under, depress farm production and disrupt the sociability of local food systems. Cranbrook became a hero of ‘local’ after defeating a plan for a monster out-of-town Tesco in 1998. She has reservations all the same: ‘an amorphous aspiration … nobody knows what “local” means.’ Yet consumers love it; so do the associations of growers and suppliers who make common cause, self-consciously, to become the motor of a local food system: a hub. Last year Bidwells Agribusiness, a farm management consultant, carried out a feasibility study for a gigantic hub to service London – a ‘local food goldmine’, they reckoned, with potential demand worth £9.3 billion.

Local is now the prevailing doctrine of the alternative food movement. Many ‘locavores’ are attentive to the global food supply, yet their philosophy is based on a growing exasperation with the bigger picture beyond the parish. Overwhelmingly, in Bidwells’ research, caterers, retailers and customers say ‘knowing where it’s from’ is the main reason they prefer local. ‘Our cultural focus,’ say the authors of Local Food: How to Make It Happen in Your Community, ‘is shifting from the outward-looking exploration of the new, the far-away, the complex and the illusory to a reconnection with what’s familiar, local, simple and real.’ Even food campaigners who find this a bit too ‘simple and real’ for their liking are forced to acknowledge the virtue of local: it’s founded on production, in the gardens, fields, butteries and processing houses of Britain.

Supermarket strategists have had their eye on local for a while. Paul Kelly, in charge of ‘external affairs and corporate responsibility’ for Asda, told me of a distribution hub in Cumbria that was pouring local produce into one of his stores in Kendal (30 tubs of English Lakes ice cream are sold for every one of Ben & Jerry’s). He’s committed to the model of competitive retail, and defends his corner of the industry: it isn’t just the supermarkets driving hard bargains with producers; a handful of ‘intermediaries’ – big wholesalers and food processing giants – are at it in a major way (‘these guys have enormous power’). If you want to know who ruined the high street, blame the planners not the supermarkets.

In some respects, however, Kelly is close to the Chatham House researchers. Like Lang, he believes the vulnerabilities of the food chain will have to be addressed by diet changes. But he argues (as you’d expect) that Asda ‘sells what people want, it doesn’t sell diets’ and that government must take the lead, nudging the public towards more realistic eating. At that point, retailers would be well placed to help. ‘There’s no point selling fish from unsustainable stocks,’ Kelly reckons. ‘For example, North Sea cod’: Asda has already reached a decision on behalf of its customers about the fish stocks we’ve run down and stopped selling cod in 2006. Even though Kelly believes ‘it’s not yet deliberate’, choice-editing on the part of big retailers, informed by their sense of what can and can’t be replenished, is starting to happen. Some shoppers will be relieved to know that tough decisions in the lanes of a large supermarket are slowly being taken out of their hands.

Lang detects this development, too: ‘23-year-old store managers’ are used to ‘editing’ for turnover, he told me, so they’ve no trouble mastering the art. At the same time, supermarkets have begun, carefully, to tell us what’s good for us, in terms of health and waste. In the Sainsbury’s near Ladbroke Grove a few weeks back we were instructed in colourful lettering not to throw away broccoli stalks (they make ‘delicious soup’). Retailers are also behind the Department of Health’s five-a-day campaign: as Tesco says, pledging lower prices on fruit and veg, ‘some foods are just plain good for us.’ Kelly foresees more choice-editing in favour of healthy eating and sustainability, but worries that farmers will find it hard to respond efficiently and quickly to the new priorities. ‘Supermarkets are very fleet of foot,’ he said. ‘They can adapt to almost any environment.’ WalMart, the Asda parent, is currently ‘adapting’ to the Indian market with a new chain of supermarkets, after a setback in South Korea. The move is controversial, but Kelly has already thought it through; he goes straight to Tristram Stuart’s Waste, and glosses the passages about how much food decays in the granaries of India and Pakistan through lack of modern storage techniques: the kind of problem, he argues, that a powerful retailer can sort out.

At the end of last year, the SDC published advice to the government in Setting the Table, a study offering much more detail about what Lang, one of the drafters, meant when he spoke of diet as ‘the mediating idea’. Setting the Table is about nudging ‘consumption patterns’ towards sustainability and the role government could play in the process by beefing up its guidance to the public. So for example, the ‘Eatwell plate’, promoted by the Food Standards Agency as a sensible balance of starch, protein, fruit and veg, plus a small dollop of junk, would tell us what is good not only for us but for the environment. There is no end of these improving schemes but as Lang points out, we’ve begun to think about sustainable food supply – ‘after a lot of grumbling’ – and sustainable eating ‘shouldn’t be too much to ask’.

Setting the Table lays out 13 guidelines about how diets should be ‘modified’ with sustainability and (a big one for Lang) social equality in view, as well as health. The advantages of each recommendation are set out – and so are the disadvantages. Guideline eight, ‘reduce consumption of meat and dairy products’, cites possible iron deficiencies during pregnancy, a potential rise of osteoporosis, the decline of livestock economies and migration to cities as undesirable effects. Guideline 13 – ‘eat fish from sustainable stocks’ – foresees an increase in harmful effluents from fish farms. Invariably, the pros outweigh the cons.

Taken together, the recommendations sketch out a simpler diet than we’re used to, an equivalent for rainy, hectic Britain of what Elizabeth David discerned in the Mediterranean diet when she called it ‘the rational, right and proper food for human beings to eat’. Except there’s no romantic sense, as there was in David, of a benign landscape supporting people who understand its limits; on the contrary, we’re being told that our crowded mezzanine culture is putting serious strains on the park. By far the most arresting point is recommendation one: ‘consume less food and drink.’ Likely negative impact? Sales in the food and drinks industry. Whether you feel dismay or a tremor of relief, you can’t help noticing that after half a century of abundance, much of that time at the edge of excess, a watchdog is advising government that the party’s over.

Is that a joke? Ministers don’t have to listen to their advisers, but they may regret it if they don't. ‘Less’ is probably harder to sell than a distant war, since it’s a direct challenge to our habits on the home front; announcing it would be like preparing us for disaster, in the mind of any government. Yet perhaps we’re headed for it anyway. Felicity Lawrence reported in February that most of the price reductions trumpeted by Asda and Tesco at the end of 2009 were cuts of one penny only, while the majority of their price rises in the same period were ten times that. Food prices may not spike again as they did between 2005 and 2008, but they’re unlikely to return to 2005 levels.

The best short document about the way things go from here remains the Chatham House study, Food Futures. Hardin Tibbs, an independent strategic analyst drafted onto the Chatham House team, modelled four projections for the food supply in the short to middle term. The first proposes without much conviction that 2008 was ‘just a blip’ and habits can stay as they were. The second is a story of deferred pain: prices rise and we redouble pig and poultry production, our hopes invested in cheap meat and cheap imports of other produce, but it’s a tough, environmentally costly battle and we stand to lose in the end. In the third, the worldwide cost of producing food continues to rise while domestic production continues to fall. The gap can’t be rephrased on the markets as anything other than a food shortage; alternatives are dutifully lowered into place, like timbers in a trench. In the fourth and most disturbing model, we resemble the pharaoh, halfway through his dream in Genesis: the seven fat cattle are long out of the river, grazing the fertile plain and we’ve rolled over in our sleep. Now in the dream the seven lean cattle are clambering up the bank, baring their rotten gums and preparing to devour the seven fat cattle. They are bellowing verses from the Book of Revelation, or just quoting from the Chatham House document: ‘Multiple shocks disrupt food production and supply. Prices skyrocket as stocks plummet, triggering food shortages, famine and civil panic.’

An influential minority of consumers have responded to the call for a new food consciousness; environmentalists, media personalities (led by the heroic Jamie Oliver), nutritionists and food analysts are optimistic that it’s on the rise. Yet vast numbers of us still require nudging and guidance, and, if the food observatory is right, we will have to learn to doubt the evidence of our eyes: where they foresee austerity, we see abundance – the result of a flourishing, interconnected system of commerce which reaches its highest expression in the aisles of the larger supermarkets, stacked with produce like the wharves of fabulous ports. Why not eat what we fancy eating? And why not bin what we don’t?

Politicians can legislate away civil liberties on a good enough excuse, as we’ve seen, but they’ve been loath to come out in the open and curtail consumer choice. It wasn’t so long ago that the tobacco lobby claimed civil liberties and consumer choice were one and the same – and perhaps the assault on smoking is a precedent for regulating our intake of ‘bad’ food. Incrementally, that’s to say, with a round of restrictions on advertising here, tougher directives to retailers there, health and sustainability warnings on products, fiscal measures that penalise harmful eating and draw the wrath of the lobbies. Imagine the media in tow, thickening up the atmosphere of disapproval. It’s an unattractive prospect.

Campaigners don’t like to say out loud that food should acquire a protected status, stabilised against the turbulence of markets, as it was in the past and remains in France and the US, and shielded from over-consumption and waste. Yet if they want ‘resilience’, they will have to state their reservations about markets more clearly; and if not now, in the twilight of neoliberalism, when? Maybe only a jarring blow to our food supply would persuade us that the principle of comparative advantage no longer applied to commerce in food. But who would want the industry to own up to its externalised costs, while other parts of the economy were spared this punishing audit? Cheap food is a miracle and we’d prefer it if the days of miracles and wonders were here to stay. Still, the food observatory has warned us we’ll have to countenance a change in the way we eat – and so will the next government. Drifting into uncharted waters on a raft of voluntary codes with a sail rigged for propitious trade winds seems like a form of madness.

A digest of sources:

Waste: Uncovering the Global Food Scandal by Tristram Stuart.

Penguin, 496 pp., £9.99, July 2009, 978 0 14 103634 2

Eat Your Heart Out: Why the Food Business Is Bad for the Planet and Your Health by Felicity Lawrence.

Penguin, 352 pp., £8.99, June 2008, 978 0 14 102601 5

Hungry City: How Food Shapes our Lives by Carolyn Steel.

Vintage, 400 pp., £8.99, March 2009, 978 0 09 953168 5

Food Policy: Integrating Health, Environment and Society by Tim Lang, David Barling and Martin Caraher.

Oxford, 320 pp., £32.95, March 2009, 978 0 19 856788 2

The Memoirs of the Rt Hon the Earl of Woolton.

Cassell, 452 pp., 1959

Eating: What We Eat and Why It Matters by Peter Singer and Jim Mason.

Arrow, 400 pp., £7.99, September 2006, 978 0 09 950402 3

Food Futures: Rethinking UK Strategy by Susan Ambler-Edwards, Kate Bailey, Alexandra Kiff, Tim Lang, Robert Lee, Terry Marsden, David Simons and Hardin Tibbs.

Chatham House, 50 pp., February 2009

http://www.chathamhouse.org.uk/publications/papers/view/-/id/695/

Rising Food Prices: Drivers and Implications for Development by Alex Evans. Chatham House, 11 pp., April 2008

http://www.chathamhouse.org.uk/publications/papers/view/-/id/612/

Sir John Beddington’s speech to the Sustainable Development UK conference, March 2009.

http://www.govnet.co.uk/news/govnet/professor-sir-john-beddingtons-speech-at-sduk-09

Defra:

Food 2030. Defra, 81 pp., January

http://www.defra.gov.uk/foodfarm/food/pdf/food2030strategy.pdf

Food 2030: How We Get There. Defra, 22 pp., January

http://www.defra.gov.uk/foodfarm/food/pdf/food2030strategy-summary.pdf

UK Food Security Assessment: Detailed Analysis. Defra, 145 pp., August 2009, updated January 2010

http://www.defra.gov.uk/foodfarm/food/pdf/food-assess100105.pdf

Sustainable Development Commission:

Food Security and Sustainability: The Perfect Fit. SDC, 145 pp., July 2009

http://www.sd-commission.org.uk/publications/downloads/SDCFoodSecurityPositionPaper.pdf

Setting the Table: Advice to Government on Priority Elements of Sustainable Diets. SDC, 57 pp., December 2009

http://www.sd-commission.org.uk/publications/downloads/Setting_the_Table.pdf

‘Ethical Foodscapes’ edited by Mike Goodman, Lewis Holloway and Damian Maye. Forthcoming from Environment and Planning A.

http://www.envplan.com/A.html

The Real Choice: How Local Foods Can Survive the Supermarket Onslaught by Caroline Cranbrook.

CPRE, 15 pp., June 2006, 1 902786 84X

http://www.cpre.org.uk/news/view/30

Bidwells Property Consultancy:

http://www.bidwells.co.uk/cms.php?pageid=1031

Local Food: How to Make it Happen in Your Community by Tamzin Pinkerton and Rob Hopkins

Transition Books, 216 pp., September 2009, 978 1 900322 43 0

For a tour of Asda: http://your.asda.com