This is a best fit lookup between 2011 Output Areas (OA) and counties/unitary authorities as at 31 December 2020 in England. (File Size - 16 MB)Field Names - OA11CD, CTYUA20CD, CTYUA20NM, FIDField Types - Text, Text, TextField Lengths - 9, 9, 35FID = The FID, or Feature ID is created by the publication process when the names and codes / lookup products are published to the Open Geography portal.REST URL of Feature Access Service – https://services1.arcgis.com/ESMARspQHYMw9BZ9/arcgis/rest/services/OA11_CTYUA20_EN_LU_ce1dadcc7daa4b53abdef0aefee359c3/FeatureServer
For more information and an overview of best-fitting follow this link - https://geoportal.statistics.gov.uk/datasets/f0aac7ccbfd04cda9eb03e353c613faa/about