Censuses in the United Kingdom have been been taken every five years since 1801, but the first four were only head counts conducted by each parish and the shedules and enumerators’ books have not been kept. Very occasionally the enumerators’ notes have
survived with other parish chest documents, but at most they contain names of householders and the number of males and females living with them.
In 1841 names, occupations and ages (rounded down to the nearest 5 years for adults) were recorded along with whether or not born in the county where they were living. The enumerator recorded people household by household as he went around his area but relationships
to the head or to each other was not recorded.
The returns for 1851, 1861, 1871, 1871, 1881, 1891 and 1901 all have a similar format and are more informative. Names, ages (as supplied), marital condition, relationship to the head of the household, occupation and place of birth was recorded along with
a note of any disability. From 1891 the number of rooms occupied by the household was recorded if less than five.
With the 1911 census the enumerators’ books were destroyed but the schedule forms completed by each householder and head of institutions have survived. The questions were similar to previous years with the addition of a question to married women about how
many years they had been married and how many children, living or dead, had been born from that marriage.
1841-1901 censuses are freely available from various local archives and libraries around the country, or on-line through subscription sites such as Ancestry, FindMyPast, The Genealogist, Origins or Genes Reunited.
The 1911 census is currently only available through subscription websites or free if you visit TNA at Kew.