These notes concern the historical statistics for modern local authorities, which have been created for Vision of Britain by re-districting statistics originally reported for other units. We have also had to deal with variations in the categories and classifications used in statistical reporting over the years.

• 1841: The data come from the Occupational Abstract of the 1841 census, which cover Great Britain and which we have computerised in full. This was the first census to gather detailed information on occupations, and they are presented simply as an alphabetical list. We have assigned each to the most appropriate Division in the Standard Industrial Classification (2007), which are then further aggregated to a simplified set of "sectors" defined by us. The largest problem here is the relatively crude original reporting geography, which provides data only for county totals and selected towns.
• 1861: The data come from the tables 'Occupations of Males aged 20 Years and upwards in Districts' and 'Occupations of Females aged 20 Years and upwards in Districts', within Volume II of the Population Tables published by the 1861 Census of Population. The data were transcribed by David Gatley of the University of Staffordshire. They list 432 distinct occupations for males, and 281 for females, each of which we have assigned to the Standard Industrial Classification (2007). The original reporting geography covers 636 Registration Districts across England and Wales. As the data are for persons aged 20 and over, total numbers will be smaller than for 1841 and 1881 where our data cover all persons with an occupation.
• 1881: The data for England and Wales are derived from the full transcription of the 1881 Census enumerators' books organised by the Genealogical Society of Utah. The raw data therefore contained all the individual occupational descriptions, but we worked with a dataset supplied by Kevin Schürer and Matthew Woollard of Essex University, which had already been grouped into the 414 occupational categories used in the most detailed tables in the 1881 census reports. We then assigned each of these 414 categories to a Division in the Standard Industrial Classification (2007). The data from Essex University were geographically very detailed, being organised into roughly 15,000 parishes. The data for Scotland were computed from the tables "Occupations of the inhabitants of the county of [Scottish county name] at different Ages", and "Occupations of the inhabitants of the [type of burgh] Burgh of [Scottish burgh name] at different Ages", the table numbers varying between counties, within "Abstracts; section XV. Occupations of the people" in the Ninth Decennial Census of the Population of Scotland Taken 4th April 1881, with Report. Volume II, pp. 398-913". Redistricting for Scotland used a specially constructed GIS coverage containing boundaries for just the counties and the particular burghs for which tabulations were available, and some of the burgh boundaries were unavoidably approximate.
• 1911: The England and Wales data come from Table 13, 'Occupations (condensed list) of males and females at ages 10 years and upwards; in England and Wales, the aggregates of urban and rural districts respectively in England and Wales, administrative counties, county boroughs, Metropolitan boroughs, urban districts of which the population exceeded 50,000 persons, and the aggregates of rural districts in administrative counties', which occupies the whole of Volume II of the 1911 Occupation Tables. This is a complex table, listing 137 occupations for a typical county (Bedfordshire), but some are divisions within others. Our procedures enable the full detail to be used, assigning each occupation to the Standard Industrial Classification (2007). The Scottish data come from the even more detailed Table 22, "Occupations of males and females aged 10 years and upwards, at eleven groups of ages, and by status", in the County Reports of the 1911 Census of Scotland, which provides data for counties, the four cities and selected large towns. The Scottish data were re-allocated from those units, and from the county residuals, to parishes pro rata to population, making use of information on the relationships between burghs and parishes listed in Table 2 of the County Reports, "Particulars of parishes", then redistricted to modern districts using our parish-level GIS.
• 1931: This is the first year for which we use data on 'Industry', meaning the business of a person's employer, rather than individual 'Occupations': this distinction was becoming increasingly important as more people had jobs like 'Clerk' or 'Secretary', which could be done in any industry, although 'Labourer' was always impossible to assign. The data for England and Wales are based on full transcriptions of Table 2, "INDUSTRIES (FULL LIST). MALES AND FEMALES, AGED 14 YEARS AND OVER, EXCLUSIVE OF 'OUT OF WORK'" and the less detailed Table 3, "Industries (condensed list) of Males and females aged 14 years and over,(exclusive of persons 'out of work')", for "Urban areas with populations not exceeding 50, 000 and rural districts" in Census 1931: England and Wales: Industry Tables. Together these cover all individual local government districts in the country, and county residuals have been used to estimate numbers in each category in the more detailed Table 2 for the districts covered only by Table 3; and then these categories have been assigned to the Standard Industrial Classification (2007). The data for Scotland are based on Table 16, "INDUSTRIES OF MALES AND FEMALES, AGED 14 YEARS AND OVER, IN CITIES, COUNTIES AND LARGE BURGHS", in Census 1931: Scotland: Occupations and Industries. This uses the same classification as England and Wales, but there is no simplified table for other districts, so the county residuals after deducting numbers in Large Burghs have been allocated to the Small Burghs and Districts of County pro rata to their populations of working age (15-64) males and females.
• 1951: Like 1931 these are data on Industry, not Occupation, and for the first time they are based on where people worked, not where they lived. This of course has a particularly large impact on the London area. The data for England and Wales are based on full transcriptions of Table 2, "INDUSTRIES (Minimum List) and Status Aggregates, OCCUPIED MALES and FEMALES aged 15 and over" for "Conurbations, Administrative Counties, County Boroughs, Metropolitan Boroughs and Urban Areas with 50,000 Population or more", and Table 3, "Industries (Orders and Selected Units) and Status Aggregates, Occupied Males and Females aged 15 years and over" for "Urban areas with Populations of Less than 50, 000, Rural Districts and New Towns", in Census 1951: England and Wales: Industry Tables. County residuals have been used to estimate numbers in each category in the more detailed Table 2 for the districts covered only by Table 3; and then these categories have been assigned to the Standard Industrial Classification (2007). The data for Scotland are based on Table 13, "Industries of Occupied Population aged 15 and over by Place of Work. Scotland, Cities, Counties and Large Burghs" Census 1951: Scotland: Industry Tables. This uses the same classification as England and Wales, but there is no simplified table for other districts, so the county residuals after deducting numbers in Large Burghs have been allocated to the Small Burghs and Districts of County pro rata to their populations of working age (15-64) males and females.
• 1971: The data for England and Wales were transcribed from Table 3, "Industry and status by area of workplace and sex" for "County, county boroughs, urban areas with populations of 50,000 or more, conurbation centres (10% Sample)", as published in the Economic Activity County Leaflets for the various counties. The data were originally presented using the Standard Industrial Classification (1968), but we have re-assigned individual categories to the 2007 version. Data for the London Boroughs were not redistricted using our GIS system, but directly assigned as their boundaries have not changed since 1965. The data for Scotland were transcribed from Table 3, "Industry and status by area of workplace and sex (10% sample)" for "Planning sub-regions, cities, counties, large burghs, county remainders, conurbation centre, new towns", in the Scottish 1971 Economic Activity Tables. Before re-districting to modern units, the county residuals after deducting the figures for Large Burghs were allocated to the Small Burghs and Districts of County pro rate to their total populations of men and women.
• 1991: This is based on Table WB9, "Industry divisions/classes (1980 SIC): Employees & self-employed (SWS Set B - Persons working in zone) [10% Sample]" from the 1991 Census of Population, using data for all "Frozen 1991 Wards" downloaded from the NOMIS online system. However, while this is geographically very detailed, it provides data only on sixty industrial "Classes", as defined in the Standard Industrial Classification (1980). We therefore also used the "employee analysis" from the 1991 Census of Employment which rovides data for 335 "Activities", but only for whole local authorities: we used the latter to estimate numbers in each ward in each of the Activities, which were then re-assigned to the Standard Industrial Classification (2007). Two Activities had to be treated specially as the Census of Employment provided no data, 100 "Agriculture and horticulture" and 9900 "Domestic services". However, each formed the whole of an SIC(1980) Class, so we could directly use the ward-level data. The London Borough were again directly assigned rather than redistricted.
• 2011: The data were taken directly, without re-classification or redistricting, from Table WP605EW, "Industry (Workplace population)" for England and Wales, and Table WP605SCca, "Industry - workplace population" for Scotland. These tables do not provide a break-down by gender, and the Scottish table uses a slightly more limited classification.