Cripes! The Mayor is backing a Leftie plot

However, Boris Johnson is tearing up such preconceptions. He appears determined to nanny Londoners into eating their greens, which will be distributed according to principles closer to Karl Marx than Adam Smith.

Johnson's "Capital Growth" plan to grow food in London, launched last November, is reportedly proceeding apace. The Mayor has made Rosie Boycott London's "food champion". Ms Boycott achieved notoriety as editor of the Independent on Sunday when she launched a campaign to legalise cannabis. A decade on, she does not want us to grow our own dope but our own veg.

I wanted to mock her plan to create 2,012 food growing spaces in London in time for the 2012 Olympics. But even this grumpy cynic had to admit that the whole venture is rather inspiring.

Spare bits of land are being found all over town by canal sides, in school playgrounds, near Marble Arch, on the roof of the Hayward Gallery, on council estates and at the Latchmere House prison.

I thought that the main problem would be stopping passers-by stealing the food. Vegetable plots in a prison grounds should be secure. And I don't believe struggling artists are so hungry they would scale the walls of the Hayward to steal a lettuce. But what about the plots on open ground?

Seb Mayfield, who is helping organise gardening groups across London, told me I was worrying unnecessarily. The aim of the enterprise was to improve Londoners' often appalling diets. Many gardeners would be happy for people to pick up fresh fruit and veg for nothing as they passed by. As long as they tasted decent food for the first time in years, it would not matter.

So on a council estate, the food would be distributed via the residents' association. At a school, children would be given vegetables to take back to their mothers. Some groups were talking about setting up a stall and handing out produce free of charge, others about selling below market rates and reinvesting money in their allotments.

Somewhat gobsmacked by his impeccable ­idealism, I searched for a counter-argument and could find only one. Junk culture has penetrated deep: what if some Londoners will not eat fresh food even if it were given to them gratis?