This paper discusses how the published census reports from 1921 up to 2011 can be used to derive information on employers and their workforce, self-employed sole proprietors, and the remaining occupied population as workers. It assesses how the content changed over time and it has to be managed to obtain comparability and alignment with the earlier censuses for 1851-1911 to allow a continuous time series for 1851-2011. This gives the definitions and background to the data used in Bennett et al. (2019) 'The Age of Entrepreneurship: Business Proprietors, Self-employment and Corporations since 1851' (Routledge); and also how BBCE data can be linked to modern censuses