The 1911 and 1901 Government Censuses are some of the earliest existing comprehensive national censuses available for research. There are some fragments available for 1821 but most were destroyed by fire. The Census are now available free of charge online and they can offer useful information for your research.
The Census provide valuable information regarding the type of houses within which families lived. As well as general information regarding the members of the household, county of birth and occupation, the 1911 Census provides greater detail about the number of children born and still living and number of years married. The recording of county of birth is very useful in attempting to trace those who migrated within the country. While ages are recorded for each member of a household these should be treated as approximate. Many people would not have known their actual date of birth.