It turns out to be better for the environment to truck in tomatoes from Spain during the winter, for example, than to grow them in heated greenhouses in Britain.

Any winter tomatoes are grown in greenhouses, even in Spain. OK, not heated as British greenhouses would be. But is this a real choice? Are there British greenhouse tomatoes on the market in any great quantity? What's better for the environment, anyway, is not only to consume local spacewise, but also timewise, in other words eat fruit and veg in season. Winter greenhouse tomatoes are rubbish. Why buy them? (Unless occasionally if you must).

it transpires that half the food-vehicle miles associated with British food are travelled by cars driving to and from the shops. Each trip is short, but there are millions of them every day.

Why, sure. So let's truck and fly food in, and people will stop driving to and from the supermarkets?

The whole point made about cars (an SUV with one salad aboard, or people driving around buying stuff from farms, etc) ignores of course that people who choose to buy local tend to be aware of these problems. One trip to farmers' market is better than several to local producers.

Research carried out at Lincoln University in New Zealand found that producing dairy products, lamb, apples and onions in that country and shipping them to Britain used less energy overall than producing them in Britain.

It would, wouldn't it? I have my doubts.

even if flying food in from the developing world produces more emissions, that needs to be weighed against the boost to trade and development.

Righty-ho. This is where we know we're reading The Economist.