In Cormac McCarthy's The Road, (the film of which is out this weekend), the only food left is in cans. In a post-apocalyptic wasteland, a father and son scavenge for tinned goods. "Chili, corn, stew, soup, spaghetti sauce. The richness of a vanished world."

Is this a vision of our not-too-distant future? Will we soon be stockpiling canned mandarin segments and clawing one another's eyes out for the last tin of powdered milk in Tesco? It's not a nice thought, but it's one that food campaigners have been begging us to face up to for some time now. In this uncertain world, we can no longer take our food supply for granted. For years, academics such as Tim Lang, Professor of Food Policy at City University, gave warning that we were "sleepwalking" into a future where our food security was likely to be seriously undermined, whether by natural disasters, rising fuel costs, climate change or the massive pressures placed on the global food system by a rising population. We shrugged it off, setting off in our cars for another wasteful trolley of ready-meals.

In 2008, American pundit Paul Roberts published The End of Food. Roberts argued that the "bullet" attacking the world's food system could come from any number of sources: avian flu, "a sharp spike in the price of oil, a series of extreme weather conditions, an outbreak of some new plant disease". Any one of these, and we'll be scrabbling in the canned goods aisles. More than one at once, and there might be no canned good aisles left to scrabble in. In April 2008, when spiralling food prices led to riots around the globe, people in Haiti were reduced to eating mud cakes.

At least that level of food anxiety could never happen in Britain. Or could it? For years, the Government told us everything was fine. This was a land of plenty. Only four years ago, Gordon Brown's Treasury assured us that food security in Britain was not an issue because we were a rich country, and could buy food from wherever we chose, as if the world were our personal larder. Now, finally, as The Sunday Telegraph reported last week, the Government has woken up to the problem. A new report launched on Tuesday entitled Food 2030 gives a warning that Britain can no longer afford to be complacent. "We need to think differently about food," said Gordon Brown in his foreword to the report, produced by the Department for Environment, Food and Rural Affairs (Defra). Setting out a new food strategy for the next two decades, the report says that the industry needs to prepare for "sudden shocks" such as natural disasters or price spikes. Britain will need to produce more food, we are told, but will have to do so sustainably, "without damaging the air, soil, water and marine resources, biodiversity and climate that we all depend on".

Here was a long overdue acknowledgment that farming is actually pretty essential. Unlike Gordon Brown, food is something we can't do without. Labour has hardly been the countryside's best friend. But at last, the "2030" report tells us the obvious truth that "the natural environment and the economy are intrinsically linked". The food and farming sector employs 3.6 million people. It is in everyone's interests to see this sector thrive. Britain will never be 100 per cent self-sufficient: life would be miserable without the imported pleasures of coffee, tea or spice. But the more food we can produce locally, the more secure our food supply will be in the event of sudden blips in the supply chain. UK farming, states the Defra report, "should produce as much food as possible, as long as it is responsive to demand".

Well said! Except that very little in the report suggests that this dying Labour government is going to take any serious steps to make the necessary renaissance in British farming come about. The Government wants us all to eat a "healthy and sustainable diet". Yet instead of any real reform, we are directed to "an enhanced eat-well website". There is a pointed lack of any mention of organic food. The report blethers about such things as the "milk roadmap" and the "fruit and vegetable task force". But there is no serious new injection of either money or laws to aid farmers. Sustain, a lobbying alliance for better food and farming, has already attacked the report as "soft", complaining that it constitutes a "series of minor tweaks to our fundamentally unsustainable food system".

By raising the idea of improving self-sufficiency, the "2030" report only brings home the extent to which we have moved in the opposite direction in recent years. The problem of food security goes far beyond this country, but even by the standards of our European neighbours, Britain performs badly.

Look at fruit. In 1963, we grew around 30 per cent of our own fruit; now it is closer to 5 per cent. Compare this with France, which in 1963 grew enough fruit to feed 90 per cent of the population and still produces enough to feed 80 per cent; or Italy which produced around 110 per cent of its fruit needs in 1963 and still does today. We may not have Italy's sun-kissed orange groves, but we could still do better with the land we have. Over the past 13 years, our self-sufficiency in food overall has plummeted from 75 per cent to 60 per cent.

Take dairy. Our milk and cream are among the best in the world. Give a spoonful of British double cream to a Frenchman and he will swoon. Yet our dairy farmers are in a quandary, unable to sell their delicious product for more than it costs them to produce it. A litre of milk costs the consumer 70-80p, of which the farmer gets only 21-28p, the same as it costs to produce. No wonder countless dairy farmers leave the industry.

There is a similar predicament in the honey industry. There is huge demand for British honey, boosted partly by awareness of the worrying collapse in honeybee colonies. Yet in many shops, all native honey is gone by halfway through the year. Of the 400g of honey per person we consume every year, only 80g is British. The reason? We currently have a mere 300 professional beekeepers in this country, many of them nearing retirement age. It will only get worse unless something is done. When I attended a forum on the future of honeybees at No 10 Downing Street last September, many well-intentioned words were spoken about saving British bees and honey. Yet when I suggested to a Government advisor that they might think of subsidising honey farmers, he laughed nervously.

It is all too easy to attack the "2030" report for its typical Brownian mix of hypocrisy and impotence. I wonder, though, how many of us really have the stomach for root-and-branch reforms of our farming system. The Conservatives have said that they want action on sustainable food "with a supermarket ombudsman and legislation to enforce honest labelling if the retailers won't act". But David Cameron has stopped short of spelling out what the "sustainable farming" he favours might really entail.

Biologist Colin Tudge, organiser of the Campaign for Real Farming, says that our politicians are "dangerously deluded" about farming. "Feeding people is easy," says Tudge, but only if our farmers switch to a "maximum variety" system of agriculture which puts plants first and meat second. This would involve a complete redesign of agriculture.

The odds are, we won't get the crisis measures we need for our food system until the crisis has already hit. So let's hope that The Road is just a scary story, not a prophecy.

Bee Wilson writes The Kitchen Thinker column in Stella and is the Guild of Food Writers' food journalist of the year