It is for individual local planning authorities to assess if land is grey belt and to determine whether to amend Green Belt boundaries through the preparation or updating of plans.

The government does not hold data on how much land has been formally identified as grey belt land by local planning authorities.

The government monitors and publishes annual statistics showing the extent of England’s Green Belt, including changes resulting from land being released from, or added to, the Green Belt. The 2024-25 statistics are available on gov.uk here and those for 2025-26 are due to be published on 22 October.