| London, England, Electoral Registers, 1832-1965 | 179,071,659 |
| UK, Electoral Registers, 2003-2010 | 65,218,080 |
| West Yorkshire, England, Electoral Registers, 1840-1962 | 46,743,829 |
| 1939 England and Wales Register | 45,915,107 |
| UK, Electoral Registers, 2011-2018 | 45,527,705 |
| Surrey, England, Electoral Registers, 1832-1962 | 36,618,572 |
| Glamorganshire, Wales, Electoral Registers, 1832-1978 | 35,226,372 |
| 1911 England Census | 33,833,357 |
| Liverpool, England, Electoral Registers, 1832-1970 | 32,578,653 |
| 1901 England Census | 30,578,247 |
| Glasgow, Lanarkshire, Scotland, Electoral Registers, 1857-1962 | 30,247,020 |
| 1891 England Census | 27,127,825 |
| 1881 England Census | 24,766,987 |
| 1871 England Census | 21,398,265 |
| East Sussex, England, Electoral Registers, 1705-1963 | 20,425,086 |
| Edinburgh, Scotland, Electoral Registers, 1832-1966 | 19,784,218 |
| 1861 England Census | 18,433,370 |
| Bedfordshire, England, Electoral Registers, 1832-1986 | 17,982,265 |
| 1851 England Census | 16,681,328 |
| Gwent, Wales, Electoral Registers, 1832-1969 | 16,295,916 |
| North Yorkshire, Electoral Registers, 1832-1971 | 15,054,046 |
| 1841 England Census | 14,772,290 |
| Aberdeen City and Former Counties of Aberdeenshire, Scotland, Electoral Registers, 1832-1976 | 14,346,425 |
| Westminster, London, England, Electoral Registers, 1902-1970 | 13,360,481 |
| Berkshire, England, Electoral Registers, 1840-1965 | 12,738,603 |
| Gloucestershire, England, Electoral Registers, 1832-1974 | 11,544,708 |
| Newcastle upon Tyne, England, Electoral Registers, 1741-1974 | 10,239,239 |
| Kensington and Chelsea, London, England, Electoral Registers, 1889-1970 | 9,747,012 |
| Midlands, England, Electoral Registers, 1832-1965 | 9,182,437 |
| West Sussex, England, Electoral Registers, 1832-1963 | 8,208,872 |
| Worcestershire, England, Electoral Registers, 1837-1974 | 8,183,878 |
| 1911 England Census Summary Books | 7,555,402 |
| Fife, Scotland, Electoral Registers, 1914-1971 | 6,676,703 |
| Cambridgeshire, England, Electoral Registers, Burgess Rolls and Poll Books, 1722-1966 | 6,234,037 |
| Swansea and Surrounding Area, Wales, Electoral Registers, 1839-1966 | 5,918,713 |
| Lancashire, England, Electoral Registers, 1832-1939 | 5,022,103 |
| UK, Poll Books and Electoral Registers, 1538-1893 | 4,677,818 |
| Norfolk, England, Register of Electors, 1832-1915 | 4,481,061 |
| 1901 Scotland Census | 4,470,512 |
| 1891 Scotland Census | 3,973,948 |
| Sutton, Surrey, England, Electoral Registers, 1931-1970 | 3,823,324 |
| Bexley, Kent, England, Electoral Registers, 1734-1965 | 3,753,187 |
| 1881 Scotland Census | 3,728,099 |
| Pembrokeshire, Wales, Electoral Registers, 1740-1978 | 3,432,144 |
| 1871 Scotland Census | 3,365,759 |
| Former British Colonial Dependencies, Slave Registers, 1813-1834 | 3,178,595 |
| 1861 Scotland Census | 3,062,857 |
| 1851 Scotland Census | 2,921,840 |
| 1841 Scotland Census | 2,594,717 |
| Aude, France, Censuses, 1810-1906 (in French) | 2,573,204 |
| Perth and Kinross, Scotland, Electoral Registers, 1832-1961 | 2,477,867 |
| 1911 Wales Census | 2,460,733 |
| 1901 Wales Census | 2,035,182 |
| 1891 Wales Census | 1,760,678 |
| Anglesey, Wales, Electoral Registers, 1832-1977 | 1,602,837 |
| 1881 Wales Census | 1,588,506 |
| Dorset, England, Electoral Registers, 1839-1922 | 1,584,958 |
| 1871 Wales Census | 1,412,692 |
| 1851 Wales Census | 1,168,790 |
| 1861 Wales Census | 1,151,033 |
| 1851 United Kingdom Census Sample | 994,793 |
| 1841 Wales Census | 987,719 |
| North Lanarkshire, Scotland, Electoral Registers, 1847-1969 | 714,769 |
| Ireland, Tithe Applotment Books, 1805-1837 | 606,726 |
| 1911 Wales Census Summary Books | 522,671 |
| Fife, Scotland, School Admissions and Discharges, 1867-1922 | 215,160 |
| UK, Absent Voter Lists, 1918-1925, 1939 | 174,695 |
| Web: Scotland, Rolls of Male Heads of Families, 1834-1845 | 155,106 |
| 1911 Channel Islands Census | 97,273 |
| 1901 Channel Islands Census | 96,404 |
| 1861 Channel Islands Census | 92,464 |
| 1891 Channel Islands Census | 92,202 |
| 1851 Channel Islands Census | 89,973 |
| 1871 Channel Islands Census | 89,403 |
| 1881 Channel Islands Census | 87,037 |
| 1841 Channel Islands Census | 76,077 |
| 1891 Isle of Man Census | 55,586 |
| 1881 Isle of Man Census | 55,144 |
| 1901 Isle of Man Census | 55,028 |
| 1871 Isle of Man Census | 53,759 |
| 1861 Isle of Man Census | 52,466 |
| 1851 Isle of Man Census | 52,144 |
| 1911 Isle of Man Census | 52,121 |
| 1841 Isle of Man Census | 48,033 |
| Fife, Scotland, Voters Lists, 1832-1894 | 47,875 |
| County Antrim, Ireland 1851 Census | 28,780 |
| Ireland, 1841/1851 Census Abstracts (Northern Ireland) | 24,749 |
| 1911 Channel Islands Census Summary Books | 23,512 |
| Ireland, Index of Religious Census, 1766 | 20,506 |
| Ireland, Ulster, Census of Protestant Householders, 1740 | 15,951 |
| Dunfermline, Fife, Scotland, Carnegie Music Institution Registers, 1910-1920 | 13,699 |
| 1911 Isle of Man Census Summary Books | 12,838 |
| Ireland 1766 Religious Census | 11,371 |
| County Antrim, Ireland, Householder's Index, 1851, 1857 | 10,078 |
| England, North Nottinghamshire Register of Voters, 1885 | 9,011 |
| Perth, Scotland, Survey of Inhabitants, 1766, 1773 | 8,894 |
| Burntisland, Fife, Scotland, Directory and Yearbook, 1892 | 1,279 |
| Suffolk Returns From the Census of Religious Worship of 1851 | 300 |
| Lincolnshire 1818 Poll Book | 180 |
| U.K. Census Free Sample | 157 |