The 1961 Census Microdata for Great Britain: 9% Sample: Secure Access dataset was created from existing digital records from the 1961 Census. The file contains information on individuals in local authorities and counties. Topics covered include demographics, for example family and household circumstances, employment and qualifications, migration, commuting, car ownership, and housing. The file was created under a project known as Enhancing and Enriching Historic Census Microdata Samples (EEHCM), which was funded by the Economic and Social Research Council with input from the Office for National Statistics and National Records of Scotland. The project ran from 2012-2014 and was led from the UK Data Archive, University of Essex, in collaboration with the Cathie Marsh Institute for Social Research (CMIST) at the University of Manchester and the Census Offices. The original 1961 records preceded current data archival standards and were created before microdata sets for secondary use were anticipated. A process of data recovery and quality checking was necessary to maximise their utility for current researchers, though some imperfections remain. Supplementary files are available on request