Employer response in the censuses for 1851-81 gave the number employees. This information provides invaluable national-level information on individual firms unavailable elsewhere. However, deficiencies in the census process and its digital capture have limited previous analysis. This paper develops a methodology of data re-scaling raw responses to allow for non- response and biases in digital data preparation using the BBCE standard EA17 sector codes to give a first set of estimates of firm-size by sector for 1881. The paper records work in progress; it is subject to revision of method, and updating of the firm-size estimates.