Where the data comes from

Every report names its sources beside each finding, with the date it was read. This page lists them in one place, with the licence, so you can read the same records yourself.

Postcodes

postcodes.io, an open service built on Office for National Statistics and Ordnance Survey open data. Gives the coordinates, the council and the country for a postcode. Open Government Licence v3.0. https://postcodes.io

Planning

planning.data.gov.uk, the national planning data platform run by the Ministry of Housing, Communities and Local Government. Article 4 direction areas, conservation areas, flood risk zones and flood storage areas. The platform says itself that it is not yet complete for all of England, which is why a report says not checked when a council has published nothing. Open Government Licence v3.0. https://www.planning.data.gov.uk/dataset/

Flood

The Environment Agency. The Flood Map for Planning via planning.data.gov.uk, the real time flood monitoring API for warnings, warning areas and river gauges, the Risk of Flooding from Rivers and Sea layer, and the Risk of Flooding from Surface Water map service. England only. Open Government Licence v3.0. The free official service for the public is https://check-long-term-flood-risk.service.gov.uk/postcode

Radon

The Indicative Atlas of Radon in Great Britain, produced jointly by the British Geological Survey and the UK Health Security Agency, read through the BGS open map service. Each 1 km square carries the highest radon potential found in it. Open Government Licence v3.0. Contains British Geological Survey materials copyright UKRI 2026. The UKHSA per address search costs £3.90 at https://www.ukradon.org/services/address_search and the free maps are at https://www.ukradon.org/information/ukmaps

Landlord licensing

The national mandatory HMO rule is read from the Licensing of Houses in Multiple Occupation (Prescribed Description) (England) Order 2018 and the Housing Act 2004 on legislation.gov.uk, with the plain guidance at gov.uk. Additional and selective licensing schemes come from a table we keep, one row per council, each read from the council's own published page on the date printed beside it. The table holds every London borough and the largest English councils. A council outside the table is reported as not checked. Article 4 directions on HMOs come from planning.data.gov.uk. Ward names come from postcodes.io. The council is the final authority on whether a licence is needed.

Law

Statutes are cited from legislation.gov.uk. Scottish council application pages are linked from the pages the councils publish, read on the date shown in the report.

Attribution

Contains public sector information licensed under the Open Government Licence v3.0. Contains British Geological Survey materials copyright UKRI 2026. Contains OS data copyright Crown copyright and database right 2026.