Ministers have seen the future and it is Milton Keynes in Buckinghamshire. The land of the concrete cow and the perpetual roundabout has apparently achieved greater biodiversity than the green fields it was built on. According to Caroline Flint, the housing minister, anybody worried about having one of the government’s new eco-towns built on their bit of this green and pleasant land should go on a pilgrimage to Milton Keynes. Even a large new town like this, it seems, can be environmentally friendly if designed in the right way. So why should anybody worry about a modest-sized eco-town?

Ms Flint, one of this government’s feistier ministers, has a point. The architects and planners of Milton Keynes were much mocked but had a vision in the 1960s that was ahead of its time. Green spaces were built in to the plan, not all of them carefully manicured parks. Wildlife was encouraged. The town’s extensive network of cycleways does allow its residents to travel around in a safe and environmentally friendly way. The roads are designed to minimise queueing, even in rush-hour periods, reducing carbon emissions. It has some 20m trees, the equivalent of a small forest.

Should we stop worrying about eco-towns and learn to love them? Should Dame Judi Dench and Tim Henman, among others, get down from the barricades? Probably not. As the Campaign to Protect Rural England points out, London Zoo has plenty of biodiversity but is a long way from being a natural habitat and nobody would advocate zoos all over the country. The reason eco-towns are regarded with deep suspicion is not only that they seem a contradiction in terms but also that they look like a political gimmick whose consequences will be with us for a long time. Is it really possible to have environmentally friendly settlements of 5,000 to 20,000 people? Where will they travel to work? Ms Flint’s evocation of Milton Keynes is a nice try. Convincing people of the need for eco-towns will take a lot more.