Tom Papworth is a Senior Fellow at the Adam Smith Institute.

Britain is facing a housing crisis. Homes are absurdly expensive – especially near our most prosperous cities, exactly where we need to be attracting new, young, talented workers.

The government expect that around 2.5 million new households will form over the next decade (not, contrary to popular myth, as a result of immigration, but due to the fact that young people are leaving home, pensioners are living longer and households are on average smaller). But best projections are that only around 1.4 million properties will be built over the next decade. Where can we fit the extra million homes?

The problem is not a shortage of land. Contrary to another popular myth, Britain is neither particularly densely populated, not is it over-developed. The population density of the UK is similar to that of Germany and less than Belgium, Japan or the Netherlands.

But Britain has among the lowest levels of built environment per head of any European country, which translates into smaller, more expensive homes and less business space. Narrowing down on England we find that 90 per cent of the land is either green space or water; 13 per cent of England is within the Green Belt.

By comparison, just nine per cent of England is developed, and half of that is domestic back gardens.

In a new report for the Adam Smith Institute, I examine the opportunity to develop an ample source of land that is available on our very doorstep. The only thing stopping us developing this valuable resource is an innovation of the Labour controlled London County Council under Herbert Morrison, and the Labour Government of Clement Atlee. It is the Green Belt.

Popular support for Green Belts is based on two misconceptions. Firstly, people believe that Green Belts provide access to rural greenspace for urban populations. This may be true for the lucky few who own land within a mile of the Green Belts, but the vast majority of the urban population value nearby parks and open spaces far more than they value distant Green Belts.

Yet these urban open spaces are under greater pressure because of the very policy of increased densification of cities that Green Belt policy requires.

Secondly, people believe that Green Belts are good for the environment. Quite the opposite is the case. Over a third of Green Belt land is devoted to intensive agriculture and is actively harmful to the environment: soaking fields in herbicides and pesticides creates not a rural idyll but a sterilised wasteland.

In fact, domestic back gardens are far more biodiverse than farms. Meanwhile, displacing development to exurbs and dormitory towns beyond the Green Belts requires more land to be devoted to transport infrastructure and lengthens commutes, thus increasing pollution and greenhouse gas emissions.

The official justifications for Green Belt policy are even less credible. “Preventing urban sprawl” fails either to define what “urban sprawl” is or to explain why it is okay to sprawl from Westminster to Hammersmith, from Croydon to Bexley, or from Ruislip to Enfield, but not into Surrey, Kent or Hertfordshire.

It is high time that these vestiges of socialist planning were abolished. This need not result in a free-for-all or even put at risk areas of genuine beauty or value. Abolition of the Green Belt is not intended to declare open season on ancient woodland, environmentally sensitive areas or areas that offer beautiful vistas. Land with important environmental, historic or amenity value should be protected by one of the many other designations that exist in UK law.

Failing that, at the very least Green Belt designations should be removed from all intensive agricultural land. This would liberate over half a million hectares of land for development – about the same amount as is currently built upon – while still retaining green belt designation on 150 per cent as much Green Belt as when Margaret Thatcher won her 1979 election victory.

Only a tiny fraction fo this liberated land would actually be developed – around 1.5 per cent of the current Green Belt. It is hard to believe that turning fields of rapeseed between Romford and Woodford into new villages would be anything but beneficial.

But there is another, even more modest suggestion that highlights just how wasteful our current land-use policy really is. If we modified our proposal still further, and only removed Green Belt designation from intensive agricultural land near London that was within half a mile of an existing railway station, we could still build the extra million new homes Britain needs.

Ideally it shouldn’t be for governments to proscribe where private enterprise can flourish, or where people can live. But the new government in May will have to begin from here. And there is an enormous opportunity for any government willing to tackle the absurdity of the Green Belt to overcome the housing crisis, create millions of new jobs, and match the impressive record of development of the governments of Harold MacMillan and Stanley Baldwin.