A best fit lookup between 2011 Middle Layer Super Output Areas (MSOAs), built-up area sub-divisions (BUASDs), built-up areas (BUAs), local authority districts (LADs) and regions as at 31 December 2011 (File Size 998KB).REST URL of Feature Access Service – https://services1.arcgis.com/ESMARspQHYMw9BZ9/arcgis/rest/services/MSOA11_BUASD11_BUA11_LAD11_RGN11_EW_LU_3aef3be2ae364e668580cddbb1ca6592/FeatureServer
For more information and an overview of best-fitting follow this link - https://geoportal.statistics.gov.uk/datasets/f0aac7ccbfd04cda9eb03e353c613faa/about