The IPCC climate change report last week said agricultural productivity is likely to reverse. The British Isles are neither small nor huge. We have quite a bit of rain, a varied soil and geology. We have long winters compared with Southern Europe, but generally our weather is quite mild. Not a bad inheritance and location in food-growing terms. We ought to be planning for resilience. Instead, we are growing less and importing more.

Consider our land use. We have 17.2 million usable hectares. Fifty per cent is to cereals; 22% temporary grass; 13% oils (of the plant variety, not fracking, quite yet!); 8% other arable crops; just 3% to horticulture and 2% to potatoes.

“Nearly half our usable land is feeding animals. This is inefficient”

Half the grains are fed to animals, as is the grass. So nearly half our usable land is feeding animals. This is inefficient.

Now think health and reducing costly NHS burdens. Current advice is to eat five portions of fruit and veg a day, a number imported by Department of Health from the US in 2002. The US then upped advice to seven-a-day, but now its MyPlate nutrition guide says to make fruit and veg half of whatever you eat in a day; more veg than fruit. The Greeks suggest nine-a-day, of which one should be ‘wild greens’ (ie herbs). The Australians recently went for ‘2+5’ (two fruit + five veg).

The British mostly currently fail to meet even the weak five-a-day target. Only 31% of adults aged 19 to 65 met the recommendation, whereas 37% of people older than 65 did so. This is the World War Two education effect. Eat your greens! Only 11% of boys and 8% of girls eat their five-a-day. The health gain would be immense if we ate more. A UCL study last week published strong evidence that increasing to seven a day or more reduces mortality. Consuming vegetables and salad is more protective than fruit, but frozen or canned fruit consumption actually reversed the positive effect.

In 2012, UK land used for vegetables declined to 119,000 hectares - use for fruit was unchanged. The government’s policy is to increase UK food exports. This is failing. The food trade gap is immense and widening. In 2012, the UK imported fruit and veg worth £4.6bn, exporting just £0.2bn. We need more plants, fewer animals.

Tim Lang is professor of food policy at City University London