A senior vice-president of the American agribusiness giant says that export curbs are no solution to global crises

Our government is in a flap about food; the world prices of staples such as wheat, rice, corn and milk powder doubled and tripled between 2007 and 2008, provoking food riots, hoarding and panic in developing countries, before tumbling back in the recession. Hilary Benn, the Environment Secretary, wants Britain to have a "food strategy".

It does not impress Paul Conway, a senior vice-president and board director of Cargill, the American agribusiness giant. He reckons that governments are, as usual, getting it all wrong about food.

In August, Mr Benn stepped into the media spotlight with his thoughts about food security. He wants us to think about producing more food in Britain and has launched a consultation: is our food supply adequate, is it sustainable and kind to the environment and do we waste too much food?

The global food supply is the daily bread of Cargill, one of the world's top grain traders, alongside ADM, Bunge and Glencore. According to Mr Conway, this war-economy notion of growing more of our own food, of eating our plates clean, is a terrible muddle and causes more harm than good. The man from Cargill says that he is worried about food security but for Cargill, the big problem is not whether we will have enough food on the table, but whether it will be safe to eat.

"What is unfortunate is that the discussion revolves around food selfsufficiency. We think the two things are different." Talk about self-sufficiency and government intervention, hoarding, market intervention and price controls, is, he thinks, "daft". Defra - the Department for Environment, Food and Rural Affairs - should not be tempted to tell farmers what to grow and how much. Nations should stick to growing what they are good at and trade surpluses.

"This is a small and crowded island. The UK has a competitive advantage in dairy but for years it was not allowed to produce because of [European Union] milk quotas. One of the most popular vegetable oils in this country is sunflower oil. You don't grow a lot of sunflowers in Britain." Nor do we grow many olives.

What keeps Mr Conway awake at night is the next outbreak of food contamination. He wants tighter rules and better enforcement and points to the recent melamine poisoning scandal in China. "That is the stuff we worry about - the supply chain, making sure every link is safe. Markets go up and down and we want to make more money, but the thing we worry about is safety."

The upward escalator of 2007-08 made a lot of money for Cargill. The company earned $3.9 billion (£2.39 billion), the biggest profit in its 140-year history. Yet the subsequent market crash and banking crisis hurt Cargill's financial trading division and profit for the year to May fell to $3.3 billion on turnover of $116 billion.

Rampant commodity prices pushed the shy grain merchants into the spotlight as the world fretted about food running out, the spectre of famine recurring in Asia and the need for a new Green Revolution if the world is to feed an extra 2.5 billion by 2050. Mr Conway found himself dragged at short notice into a video conference with China's central bank governors. "The questions were: what is causing this, what are other governments doing and what recommendations do you have for us?"

It was a "perfect storm", Mr Conway told them, a confluence of events with no specific driver. Drought in Australia and Argentina, floods in Eastern Europe, government low-carbon diktats diverting grain into biofuel, expensive crude oil that drove up the cost of fertiliser and cheap money that fuelled hedge fund speculation. No single factor made all the difference.

"Biofuels and cheap money had been around for a number of years. If you had to say what was the trigger, it was the weather issues - we saw a 50-60 million tonne drop in grain crops worldwide in one season."

Stocks of grain had run down after years of weak prices and underlying it all was what Mr Conway calls a "good news story": hundreds of millions of people in developing countries with more money, eating a better diet, including more meat. The bad news, he says, is that some of the "good news story" has now gone away.

Could this perfect storm recur? Yes, says the Briton who joined Cargill as a graduate trainee. It is happening in sugar, where a drought in India caused by the partial failure of the monsoon has severely cut sugar-cane production, causing financial disaster for peasant farmers. The price of raw sugar has run up 80 per cent since the beginning of the year, reaching a 28-year price peak.

These intermittent crises provoke what Cargill believes are bad policy decisions - stockpiling, hoarding and export curbs. Whether it was EU butter mountains or the international agencies set up in the early 1980s to manage markets in commodities, such as cocoa and sugar, all came into disrepute, Mr Conway says.

The reason they failed is that governments forgot the role of farmers. "When governments have held a lot of stock, such as in the Soviet Union, [price] signals did not get through to farmers. Last year, the Argentinian Government increased export tariffs, which meant there was no point in planting. You had grain rotting in some countries last year because governments banned exports."

Instead of trying to manage food output, governments need to invest, he suggests, in infrastructure, irrigation, ports and, counterintuitively, he says that developing countries should sponsor futures markets.

"To blame futures markets for causing problems is nonsense. What they do is give clear price signals. We are a great believer in giving price signals to farmers. A futures market is a tool, a bit like biotechnology. If there is a crisis, blaming the tool is not ... wise."

It's a message that many don't want to hear - that futures markets are the answer, not the problem, that genetically modified food is part of the solution to feeding the extra billions.

Cargill has a graph that shows the relative impact of improved yields and field acreage on global food production since 1975. Yield gains from improved seed and irrigation technology have almost doubled output, while the land under cultivation has barely changed.

We may now have a problem. "We have started to see some drop in global yields," Mr Conway says. But there is a huge amount of uncultivated land in the former Soviet Union and in Brazil "without touching a single acre of rainforest".

The other solution, he says, is GM. The Green Revolution of the 1970s, which brought high-yielding strains of wheat and rice to developing countries was largely funded by governments.

Since then, governments have cut their funding to agricultural research. The revolution in biotechnology and GM crops has been funded privately by firms such as Monsanto and Syngenta, but it is not enough and governments need to return to the labs, Mr Conway suggests. "It is a tool. To ban it is daft."

Cargill's early support of the case for bioengineered seed (although the company has no financial interest in GM) won the grain merchants no friends in Europe.

It was "incredibly badly handled", admits Mr Conway, who remembers attending meetings at 10 Downing Street over the GM crisis. It will be fully accepted in Europe only when consumers see obvious benefits, which could take a decade - and Britain, he thinks, suffers from an almost philistine scepticism. "There is more distrust of science in Britain than in any other country in the world."

Nor is he impressed with the nation's general understanding about where its food comes from. He was astonished to discover that staff at the Downing Street policy unit were unaware that Tesco did not own the factories that produced the grocer's own-branded products.

Cargill may be partly to blame for ignorance about how the food chain works. It is the least-known of the world's top companies. More than willing to talk about the controversy over GM food and futures markets, Mr Conway becomes distinctly guarded over relatively simple questions about Cargill.

Is Cargill the biggest of the grain traders? "We prefer to think of ourselves as the broadest in geographic cover and range of products." Asked about market shares in specific products, the conversation becomes even more tight-lipped. He suggests that he would be surprised if Cargill's share of wheat was "as high as 10 per cent" and its biggest products, corn and soybean, would be in the "teens".

Mr Conway attributes Cargill's shyness to being private, with 90 per cent of the firm owned by the Cargill-MacMillan clan, the family descendants of the two founders. The remainder is held by senior management. The company is an intermediary and a processor, owning few consumer brands, but interest in it is intense among those who monitor the food industry. Cargill has been under US Government scrutiny on more than one occasion, first in 1938, when it was barred from futures trading in Chicago, accused of trying to manipulate the corn market.

Ten years ago, the Department of Justice (DoJ) forced Cargill to make large divestments as a condition for its merger with Continental, then a leading competitor. At the time, the DoJ found huge market concentration with four firms - ADM, Bunge, Cargill and Continental - accounting for 70 per cent of all American corn exports and 62 per cent of all soybean exports.

It is market power in the stuff of life itself and, as a law graduate, it fascinated Mr Conway, who remembers 30 years ago reading the recruitment brochure. "Across the page, a series of time clocks around the world and the anatomy of a trade. A piece of information picked up in Asia, translated to an office in Europe and translated to an office in Buenos Aires. I thought it was fascinating and I wanted to find out more."