First they came for your light bulbs; then they went for your plastic shopping bags. Now they want you to zip it up. The government’s “green” adviser, Jonathon Porritt, chairman of the Sustainable Development Commission, says couples who have more than two children are “irresponsible”. Our offspring leave an unacceptably large environmental footprint, as well an infernal mess in the bedroom. They are warming the planet to boiling point.

The message is hardly new, although the green twist is novel. Prince Philip, the father of four children, used to bewail the perils of overpopulation from the comfort of his royal residences in the 1960s. Third World governments put the rhetoric into action. Communist China restricted peasants to one child and India, in a brief flirtation with dictatorship under Sanjay Gandhi, dispensed with offering transistor radios as an inducement to voluntary sterilisation and turned to involuntary methods instead.

A burgeoning population obviously does put a strain on resources but, as with many such arguments about limits to growth, the pressures were oversold. It was claimed in the 1960s that mass starvation would be humanity’s fate. The green revolution in agriculture met rising population demand. Two centuries ago industrialisation and technological ingenuity confounded the Rev Thomas Malthus, the original catastrophist whose Essay on the Principle of Population made dire predictions about the breeding habits of the lower classes. There is a stronger case to say that a rising population is responsible for destroying the habitats of creatures other than humans on this planet.

To be fair to Porritt, he has nothing so odious as a compulsory sterilisation programme in mind. He wants to improve state-sponsored family planning and educate us all in the error of our ways. In developing countries the education and prosperity of women are probably the best routes to reversing the rate of increase. Still, not all his assumptions should go unchallenged. It is true that the population of the United Kingdom is increasing, but immigration and and fertility rates among newly naturalised immigrants are largely responsible for the phenomenon. Only yesterday the government was warning us that declining birth rates meant we would have to import more cheap foreign labour.

Can we look forward to government missionaries preaching continence to the immigrant communities and underclass of Britain? No, this message will be directed at the guilt-stricken middle classes, who already strive to do their bit for social responsibility. Now they have an extra burden. Thanks, Jonathon.