The green belt was drawn to stop towns spreading into each other and to keep the countryside open. Much of it does exactly that. Some of it doesn't.

A field hemmed in by a bypass, a housing estate and a railway line is still green belt on the map. But it does little to stop sprawl, keep towns apart or protect the countryside. Government now calls land like this grey belt.

In plain terms, grey belt is green-belt land that is either previously developed, such as old farmyards, former depots, disused buildings and hardstanding, or not doing much for the green belt: land that makes no strong contribution to stopping towns sprawling, keeping neighbouring towns separate, or preserving the setting of historic towns.

Land protected for other reasons, such as heritage assets, national landscapes, sites of special scientific interest, ancient woodland, areas at high flood risk and the like, can still count as grey belt under this test. Those protections aren't ignored: they're weighed separately, when the actual planning application is judged, alongside everything else that matters about the site.

Not every field on the edge of a village qualifies. Most don't. But the ones that do now have a route to planning permission that didn't exist before.
 

Before the change, building homes on green-belt land needed "very special circumstances". In practice that meant almost every application was refused, and most appeals were lost.

Now, where a council can't show it has enough land for the homes it needs, building on grey belt is no longer treated as harmful to the green belt in the way it was. The application is judged on its merits: is the site in a sustainable place, is the scheme well designed, does it meet the golden rules?

Most councils in the south-east can't show that they have enough land. That is what has changed the odds, and it's why you may have received a letter from us.