Nomis
Nomis, run by the Office for National Statistics, is the go-to home for detailed UK labour market and census statistics. It holds official figures on employment, unemployment, earnings, benefits claimants, and population, plus the full census tables (2011 and 2021) and business counts, and it lets you drill right down to small geographies: regions, local authorities, wards, and output areas.
You can build queries interactively on nomisweb.co.uk, choosing a dataset, the geography, and the variables you want, then export the result. For anything programmatic there is a well-documented API that returns CSV or JSON, so you can pull specific tables and areas on demand rather than downloading whole datasets by hand. Guest access is fine for most uses, and the API takes an optional key for heavier work. Because you can request exactly the cells you need, it is straightforward to script a pipeline that fetches, say, unemployment by local authority and writes each row out as a short sentence for embedding.
Nomis is best for a UK statistics assistant that needs to ground answers about local labour markets and demographics in official numbers: "What was the unemployment rate in Leeds at the last census?" It suits any RAG system where a user asks place-and-figure questions and you want authoritative, small-area data behind the response.
The main thing to plan for is that this is numeric table data, not prose, so the useful work is turning cells into clear natural-language records and keeping the dataset, geography, and time period attached so an answer stays unambiguous. The geography and dataset codes take a little learning, and very small counts may be rounded or suppressed for confidentiality. The data is published under the Open Government Licence v3.0, so commercial and personal reuse are both fine as long as you credit the source. Alongside the wider ONS releases and NHS England Digital, Nomis is the specialist for labour market and census detail.
Related sources
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data.europa.eu
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data.gov
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data.gov.uk
The UK Government's central catalogue of open public sector data, run by the Government Digital Service. More than 47,000 datasets cover health, housing, transport, demographics, and the environment, giving RAG systems a trusted base of UK facts, figures, and official records.