06/08/2015 13:27 BST | Updated 06/08/2016 06:59 BST

In Defence of Our Green Belt on Its 60th Anniversary

The Green Belt is extraordinarily popular both with the public and with politicians.

Two-thirds of the general public say it should not be developed and in the recent general election the Prime Minister was among politicians from all parties saying how much they loved and wanted to protect it. The Green Belt still fulfils its original aims of checking sprawl, preventing towns from merging and preserving the setting of historic towns and cities. It has also delivered a more recent aim of aiding regeneration by encouraging the recycling of urban land.

So why is the Campaign to Protect Rural England (CPRE) launching a big campaign on the Green Belt's 60th anniversary?

There are two reasons. First, in spite of all the support for Green Belt, it is being steadily eroded, particularly by new housing developments. Second, as any reader of newspapers such as the Times and Financial Times will know, opponents of the Green Belt are growing in influence.

On the practical threat, some 226,000 homes are planned for Green Belt land. Planning policy states that development should only take place within the Green Belt in 'very special circumstances' and that its boundaries should only be redrawn in 'exceptional circumstances'. But these tests are not being properly applied.

The Government has responded to the launch of CPRE's Our Green Belt campaign by reiterating its commitment to the Green Belt and arguing that the 226,000 homes are 'potential developments that have not yet been agreed by their local communities, have not gone through the rigour of the planning system and are not planning permissions'.

But it is clear from evidence CPRE has gathered from across England that many local councils are designating Green Belt land for development to meet unrealistic housing targets imposed by government, or as part of their own growth strategies. So the Government must be clearer about what constitutes 'very special' or 'exceptional' circumstances. And it must intervene when councils propose to develop Green Belt land they should be protecting.

The growing intellectual assault on the Green Belt, meanwhile, is not an immediate cause of Green Belt loss, but it certainly undermines confidence in the policy and threatens its durability in the longer term.

The argument for building in the Green Belt is often pretty crude. We need more homes (true); most towns and cities with the highest demand for new housing have Green Belts (true); not enough homes are being built on available brownfield land in these places (true); we therefore we need to release Green Belt land to get the housing we need (a whopping non sequitur).

In reality, there is very little evidence that releasing Green Belt land would result in more homes, and commentators who fixate on the Green Belt ignore the big question of who is actually going to build the homes the country needs. The state, which used to build more than half of them, builds very little. Small builders, who used to account for two-thirds of private sector production, now build less than a third. And the big builders who dominate the market are clear that they have no intention of significantly increasing supply.

Whatever happens to the Green Belt, we will not get a big increase in house building because the house building sector is not capable of delivering one. Until we address that problem, including by reviving the small and medium-sized house building sector, the question of whether we build in the Green Belt is at best a sideshow and at worst an ideologically motivated attempt to undermine the planning system.

There is enough suitable previously developed land for at least a million new homes, much of it in London and the south east. If we make it easier to build in the Green Belt, these sites will be wasted and towns and cities will suffer.

But people will also suffer from the loss of Green Belt countryside. Much of it is a great amenity - think of the Thames Chase Community Forest in London or the Red Rose Forest in Greater Manchester - and all of it could be.

This community aspect of Green Belt is central to CPRE's new campaign. Our Green Belt aims to capture people's memories and experiences of Green Belt, and demonstrate why it is not only a vital planning designation, but also an important part of people's lives.

The Green Belt has been a huge success. Without it we would be immeasurably poorer. We should protect it, celebrate it, and go out and enjoy it.