We will continue to protect the Metropolitan Green Belt, as shown on the proposals map, against inappropriate development. In accordance with national planning policy, the construction of new development will be considered inappropriate and will not be permitted unless very special circumstances can be demonstrated.
Certain forms of development are not considered to be inappropriate. Proposals will be permitted where they are consistent with the exceptions listed in national planning policy and, where relevant, also meet the following criteria:

Extensions or alterations

The extension or alteration of a building provided that it would not result in disproportionate additions over and above the size of the original building.

Replacement buildings

The replacement of a building, provided the new building:

• would be in the same use, and
• is not materially larger than the one it replaces, and
• is sited on or close to the position of the existing building.