Old Generator House Mill Lane Hexton Hertfordshire SG5 3JE Data via plota.co.uk

Listed building consent is needed for work that affects the special interest of a listed building, inside or out, on top of planning permission. Setting can be a consideration for buildings nearby; there is no fixed radius.

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.

Previously an area of outstanding natural beauty, which is still the designation in law. Since 2023 authorities must seek to further its purpose, not merely have regard to it.

Registered parks and gardens, battlefields, world heritage sites and protected wrecks are designated heritage assets: harm needs clear and convincing justification.

The council must give weight to preserving or enhancing the area's character and appearance. Not every council has published its boundaries as open data.

Where development of farmland is needed, policy prefers poorer land over the best and most versatile (grades 1, 2 and 3a). Three sources: Natural England's post-1988 field surveys, which are definitive where they exist; the Defra predictive map for England (2025) and the Welsh Government predictive map, modelled from the soil map with 3a and 3b split; and the 1970s provisional map, which planners and other services still show, coarser and with grade 3 undivided. Where the provisional and predicted grades disagree, treat the predicted grade as the current estimate and expect an application to carry its own survey.