This is a best fit lookup between 2011 Output Areas (OA) and counties/unitary authorities as at 31 December 2019 in England. (File Size - 19 MB)Field Names - OA11CD, CTYUA19CD, CTYUA19NM, 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_CTYUA19_EN_LU_a11317b2d23f430a92b9a191a995d1c5/FeatureServer
For more information and an overview of best-fitting follow this link - https://geoportal.statistics.gov.uk/datasets/f0aac7ccbfd04cda9eb03e353c613faa/about