Land at Manor Farm and land north of Wraysbury Reservoir, Slough Data via plota.co.uk

Harm to a protected site is only accepted where there is no alternative and an overriding public interest.

Sites of special scientific interest are the best wildlife and geological sites in the country. Development likely to harm one is rarely permitted.

Green belt policy allows a short list of exceptions, such as limited extensions and replacement buildings. Anything else needs very special circumstances that clearly outweigh the harm. Some green belt land can count as grey belt, where it does not strongly serve the green belt's purposes. The council decides this in its green belt assessment or on each application, so we do not mark it here.

Schemes that add traffic, parking or combustion plant are assessed against the area's action plan and may need an air quality assessment.