Work in progress: data is preliminary and may contain errors.
How each authority fits
Click an area to see how it lines up with every geography.
Legend
Sources and credits
Work in progress — data is preliminary and may contain errors. Every dataset's field-by-field sourcing, known gaps and rebuild steps are in the sourcing notes.
Devolution status, mayors and profiles
Status, constituent councils, formation dates, tiers, mayors and leaders checked against gov.uk, legislation.gov.uk and each authority's own site (Wikipedia used only to find official sources). Profiles draw on government area factsheets, authority constitutions, board directories and meeting records.
Powers and budgets
Policing and fire: House of Commons Library briefing SN06104, Police and crime commissioners (July 2026). Transport: authority announcements and trade press. Budgets: each authority's own 2026/27 budget papers or approved-budget announcement — definitions differ, so figures aren't like-for-like.
Mayoral election results
Each election's Wikipedia results table, checked for internal consistency against turnout and rejected ballots. Every result links to its page.
Council control
Seats by party: Open Council Data UK, 2026 latest composition, licensed CC BY-SA 4.0. Council leaders: each council's Wikipedia page, with seven checked by hand against council or local news sources. Control is worked out from seats (a majority, or no overall control).
Area in numbers
- Population: ONS mid-year population estimates, mid-2015 and mid-2025, via Nomis.
- GDP, GVA and real growth: ONS Regional GDP by local authority, 1998–2024 edition. ONS has withheld 2024 figures for some districts while it corrects a boundary error, so eight areas show “Not published”.
- Census: Census 2021 for England and Wales (ONS, via Nomis); Scotland's Census 2022 (National Records of Scotland); Northern Ireland Census 2021 (NISRA).
Every figure is added up from council districts to each area. Download all areas (CSV).
Compare boundaries
Local authority boundaries and lookups for police force areas, ICBs, NHS regions and English regions from the ONS Open Geography Portal (2025–26 editions). Jobcentre Plus districts: DWP freedom-of-information response (February 2019) and Nomis Jobcentre Plus groups.
Maps and photos
Base map adapted from “English strategic authorities.svg” by M2Ys4U, licensed CC BY-SA 4.0 (recoloured, decorative elements removed). Mayor and leader photos from Wikimedia Commons under their own licences — photographer and licence for each are listed in the photo credits.
Licences
Contains public sector information licensed under the Open Government Licence v3.0 (ONS, NRS, NISRA, DWP). Contains Parliamentary information licensed under the Open Parliament Licence v3.0.
Design
Palette and category treatment informed by LGC's June 2023 devolution map. Card layout and interaction pattern informed by the London Constituency Maps project — structure only, not its colours or data.
About
The Devolution Explorer is a personal project, built to help people better understand devolution across the UK: who holds which powers, where, and how that is changing.
It isn't affiliated with any government department, authority or political party. The data is checked against official sources where possible (see Sources and credits), but it's a work in progress and may contain errors.
Feedback is very welcome — corrections, missing developments, or ideas for what would make it more useful.