Green belt is often thought be in place to protect countryside - it is a regional strategic planning tool. The largest Green Belt in the UK is around London with further major green belt land around the West Midlands conurbation, Manchester, Liverpool, and in South and West Yorkshire. Since 1997 an additional 30,000 hectares of greenbelt land has been designated or proposed.
Land included in the Green Belt must contribute to one or more of the five purposes set out in Planning Policy Guidance Note 2 (PPG2 Green Belts):
Local plan reviews usually prompt green belt reviews and happens every 10 years or so though areas of high housing need may demand an earlier review.