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.

• 1801-1851: The earliest censuses were head counts supplied by parish priests, rather than being based on house-by-house surveys, so we can list only the total population broken down by gender. The early reports are also somewhat confused, so we are fortunate that the 1851 census published a systematic parish-level listing including data from all earlier censuses: our redistricted data for 1801-41 for England and Wales, and 1801-51 for Scotland, is entirely based on the table 'Parishes - Area; houses, 1841, 1851; Inhabitants, 1801, 1811, 1821, 1831, 1841, 1851' in Census of Great Britain, 1851. Population tables. I. Numbers of the Inhabitants, in the years 1801, 1811, 1821, 1831, 1841, and 1851., Vol. II.
• 1851: The original 1851 age structure data for England and Wales are for Registration Districts and come from the divisional tables in Volume II, Part II of the 1851 Census Report, Ages, Civil Condition, Occupations, and Birth-Place of the People, BPP 1852-3 LXXXVIII. Currently no age structure data are available for Scotland.
• 1861: Data for England and Wales redistricted from table 2, 'Ages of Males and Females enumerated April 8th, 1861 - in Superintendent Registrars' Districts' in each of the sets of divisional tables of Volume II of the 1861 Census Report, Ages, Civil Condition, Occupations, and Birth-Places of the People, BPP 1863 LIII Pts. I and II [C.5597]. National totals are from Table I, "England and Wales. Ages of males and females enumerated April 8th, 1861, in counties", on pp. x-xi of Population tables. England and Wales. Vol. II. Part 1, 1861. Scottish national and county totals are taken from the table "Ages of the people of Scotland, and its Registration Divisions, in 1861" on pp.1-3 of "Abstracts: Ages of the people" within Census of Scotland 1861: Report Volume II., Ages, Civil or Conjugal Condition, Occupations, and Birth places of the People in Scotland. Additional data for town districts were then added from "Ages of the people in the Towns, or Town Districts, of Scotland, according to the Registration Districts, arranged Alphabetically." on p. 58 of the same volume. In constructing these data we linked data for selected urban Registration Districts to a GIS of approximate burgh boundaries, so the results are inevitably approximate.
• 1881: England and Wales data redistricted from table 2, 'Ages of Males and Females in Registration Districts' in each of the sets of divisional tables in Volume III of the 1881 Census Report, Ages, Condition as to Marriage, Occupations, and Birth Places of the People, BPP 1883 LXXX [C.3722]. National totals are from Table 1, "Ages of Males and Females enumerated in England and Wales", on page 3 of the same report. Age structures for Scottish counties and national totals are from the table "Ages of the People, in quinquennial periods, in the Registration Counties of Scotland in 1881" on pp. 4-5 of Population, Scotland, Vol. II, Section XI, "Ages of the people". All data are from Population, Scotland, Vol. II, Section XI, "Ages of the people", while data for selected burghs come from the table "Ages of males and females in each of the burghs having populations of 10,000 and upwards", on pp. 72-3 of the same report (where there was a choice, we avoided data for Parliamentary burghs). These data were then re-districted using a specially built GIS of county boundaries and approximate boundaries for these selected burghs. Data for 0-4 individual years for the National totals and county totals transcribed from "XII. Educational Statistics - Scotland and its Registration Divisions, 1881", pp78-136. Data for 0-4 individual years for the burghs transcribed from the table "Number of boys and girls at each year of life under fifteen years, and the number of these at each year of life in the receipt of education, in each of the burghs having populations of 10000 and upwards", pp138-141. Both are in Population, Scotland, Vol. II, Abstracts, Section XII. Education Statistics.
• 1891: Data for England and Wales redistricted from table 2, 'Ages of Males and Females in Registration Districts' in each of the sets of divisional tables in Volume III of the 1891 Census Report, Ages, Condition as to Marriage, Occupations, Birth Places and Infirmities, BPP 1893-4 CVI [C.7058]. National totals are from Table I, "Ages of Males and Females in England and Wales", on p. v within the introductory text of the same report. For Scotland national totals are from "Ages of the People, in quinquennial periods, in Scotland and its Civil Divisions in 1891", p. 2 in Census of Scotland 1891: Report Volume II. Part I., Ages, Education, Civil Condition, Birthplaces, Occupations, Working Status, Indices. County figures are from "Ages of the People, in quinquennial periods, in the Civil Counties and Parishes of Scotland in 1891", pp. 4-5 in the same report. Burgh figures are from "Ages of the People, in the Parliamentary Brgrhs of Scotland, having populations of 10,000 and upwards; Also in Municipal or Police Burghs of like populations, which are not Parliamentary Burghs or which have areas greater than the Parliamentary", pp.54-56 in the same volume.
• 1911: England and Wales redistricted from table 8, "Ages of Persons, Males and Females at each year of age under 21 and in Quninquennial Age-Groups in each Administrative County (inclusive and exclusive of County Boroughs), of County Boroughs, and of Rural Districts. Also Ages of Males and Females in each County Borough, Municipal Borough, other Urban District and Rural District, 1911", pp.15-201 in Volume VII of the 1911 Census Report, Ages and Condition as to Marriage [Cd.6610]. National totals are from Table 29, "England and Wales. Condition as to marriage of persons, males and females, at each year of age and in quinquennial age groups, 1911", in Summary tables, England and Wales, 1911. Data for Scotland redistricted from table 20A in each of the separate County Reports of the 1911 Census of Scotland, "Population of the county and its civil parishes by sex and conjugal condition in quinquennial age-groups". National totals are taken from Table C2, "Scotland.--Ages of Males and Females--1911 and 1901" on page lvi. of Census of Scotland, 1911. Report on the twelfth decennial census of Scotland. Volume II. (BPP 1913 Cd.8396), except for the overall total population which comes from table C1 on the previous page. Data for 0-4 years individually for the cities downloaded as a spreadsheet from Histpop taken from Table XIX "City of XXXX - Conjugal Condition and Age Distribution of Population" in each city section of the Report on the twelfth decennial census of Scotland, Vol. 1 from 1911.
• 1921: Data for England and Wales are redistricted from tables 14 and 14A, "Ages (Quinquennial groups) and marital condition" in each of the County Reports of the 1921 Census (computerisation of these data was funded by the Population Investigation Committee); however, for now we include only overall totals for compatibility with Scottish data.. We currently include for Scotland only total numbers of persons, males and females, using data not from the 1921 reports but the figures for burghs and Districts of County in 1921 listed in Table 1 in the County Reports of the 1931 Census of Scotland, "Population of Burghs, Districts of County and Parishes".
• 1931: Data for England and Wales redistricted from tables 14 and 15, "Ages (Grouped) by marital condition" in each of the County Reports of the 1931 Census (computerisation of these data was funded by the Population Investigation Committee). National totals are from Table 17, "Ages (Individual Years)", pp.125-6 in General tables, England and Wales, 1931. Data for Scotland based on table 21, "Quinquennial Age-Groups and Conjugal Condition" in the Scottish 1931 County Reports, the original listing covering burghs and Districts of County. Data for 0-4 years individually for the National totals transcribed from Table 30 "Age distribution by Single Years and Conjugal Condition - Scotland", p79 in Populations, ages and conjugal conditions, birthplaces, Gaelic speaking and housing, Scotland, Vol. II, 1931. Data for 0-4 years individually for the cities and counties transcribed from the Table 16 "Age distribution by Single Years and Conjugal Condition" plus for the 20 largest burghs from Table 16A "Age distribution by Single Years under 21 in Large Burghs" in each of the separate County Reports of the 1931 Census of Scotland.
• 1951: The original data for the local government districts of England and Wales come from table 21, "Ages (quinary) by Marital Condition", for Administrative Counties, County Boroughs and Urban Areas with 50,000 population or more, and from table 22, "Ages (quinary) and Marital Condition", for urban centres of less than 50,000 and Rural Districts, in each of the County Reports of the 1951 Census (Funding for this work was provided by the JISC 'Knowledge Gallery' initiative). National totals are from Table 17, "Age (individual years) by marital condition", pp.60-1 in Census 1951 England and Wales: General Tables. Data for Scottish burghs and Districts of County come from table 15, "Quinquennial age-groups and Conjugal Condition", in the 1951 Scottish County Reports.
• 1961: Data for England and Wales from table 6, "Age and Marital Condition -- Local Authority Areas, Conurbation Centres" in each of the County Reports of the 1961 Census (Funding for this work was provided by the JISC 'Knowledge Gallery' initiative). National totals are from Table 8, "Age (single years) and marital condition", pp.27-29 in Census 1961 England and Wales: Age, Marital condition and General Tables. Data for Scotland are from Table 6, "Age and Marital Condition", in the County Reports, covering burghs and Districts of County. National totals were added from Table 8, "Age (single years) by marital condition", pp.65-66 in Census 1961 Scotland: Leaflets: Age, Marital Condition and General Tables.
• 1971: The data for the local government districts of England and Wales come from Table 8, "Population by sex, age and marital condition" for "County, local authority areas, conurbation centres" in the County Reports of the 1971 census. National totals are from Table 9, "Population by sex, age (single years) and marital condition", pp.28-9 in Census 1971 Great Britain: Age, Marital Condition and General Tables. Data for Scotland are from table 8, "Population by sex, age and marital condition" in the 1971 Scottish County Reports.
• 1981: The original data cover the whole of Great Britain and are for "frozen wards". They are taken from Table 21, "Age and marital status of household residents", in the 1981 Small Area Statistics, and were downloaded from the CASWEB system on 27th December 2016.
• 1991: The original data again cover the whole of Great Britain and are for frozen 1991 wards. They were extracted from table S02, "Age and marital status: Residents [100%]", in the 1991 Small Area Statistics using the NOMIS online system on 11th June 2016.
• 2001: The original data cover the whole of Great Britain and are for CAS wards in England, CAS Electoral Divisions in Wales and "Standard Table" Postcode Sectors in Scotland. They were extracted from Table CS001, "Age by Sex and Resident Type" in the 2001 Census Area Statistics and were downloaded from the CASWEB system on 20th February 2017.
• 2011: Data for England and Wales come from table "DC1104EW - Residence type by sex by age", obtained from ONS Census Marketing on 6th November 2015. Data for Scotland are from table "DC1104SC - Residence type by sex by age" for local Authority areas, from the 2011 Census of Population. The data were downloaded on 17th November 2015 from the "Standard Outputs" section of the Scotland's Census website operated by National Records of Scotland. The original data for 2011 were for local authority areas, so were not redistricted.