To an economist, all types of output are equal, as long as they have customers and can be profitably produced without artificial support. Too many government ministers regard some types of output as more equal than others. They feel that they "have to do something" and to make a case for their own departmental hobbyhorse. At any one time, arguments can be heard within officialdom for subsidies to farmers, tax reliefs to manufacturing and grants to the creative industries. Government spending and taxation are increased, but the effects of throwing money at a large number of apparently deserving causes are self-cancelling.

The danger in Mr Benn's approach is that it will justify tariffs and other restrictions on imports from outside the EU, as well as increased subsidies to the UK farming sector. Alarmingly, the speech gave a nod of approval to farming "self-sufficiency", as if it would be desirable for all our food and drink to be produced in the UK.

The government seems to have forgotten that it once had a vocabulary and rhetoric that were supposed to distance it from Old Labour. Phrases like "the maximisation of production" and "food self-sufficiency" hark back to a distant era of planning and nationalisation.

The best antidote is to recall Adam Smith, and to ask whether the sponsors of maximised UK food production believe that we should maximise the growing of grapes by building "glasses, hotbeds and hot walls" in the Lowlands of Scotland.