This is a best fit lookup between 2011 Output Areas (OA) and counties/unitary authorities as at 31 December 2016 in England. (File Size - 17 MB)Column Descriptions: OA11CD | Text | 9CTYUA16CD | Text | 9CTYUA16NM | Text | 28FID | Number | 6REST URL of Feature Access Service – https://services1.arcgis.com/ESMARspQHYMw9BZ9/arcgis/rest/services/OA11_CTYUA16_EN_LU_55b671da56334fcb88d12323899cf0fe/FeatureServer
For more information and an overview of best-fitting follow this link - https://geoportal.statistics.gov.uk/datasets/f0aac7ccbfd04cda9eb03e353c613faa/about