Census 2001 was organised by the Office for National Statistics in England and Wales, the General Register Office for Scotland and the Northern Ireland Statistics and Research Agency. Detailed results by region, council area, ward and output area are available from their respective websites.
The results from the 2001 census were produced using a methodology known as the One Number Census. This was an attempt to adjust the census counts and impute answers to allow for estimated under-enumeration measured by the Census Coverage Survey (sample size 320,000 households), resulting in a single set of population estimates.
Although the 1851 census had included a question about religion on a separate response sheet, whose completion was not compulsory, the 2001 census was the first in Great Britain to ask about the religion of respondents on the main census form. An amendment to the 1920 Census Act (the Census (Amendment) Act 2000) was passed by Parliament to allow the question to be asked, and to allow the response to this question to be optional. The inclusion of the question enabled the Jedi census phenomenon to take place in the United Kingdom. In England and Wales 390,127 people stated their religion as Jedi, as did 14,052 people in Scotland.
The census ethnic groups included White (White British, White Irish, Other White), Mixed (White and Black Caribbean, White and Black African, White and Asian, Other Mixed), Asian or Asian British (Indian, Pakistani, Bangladeshi, Other Asian), Black or Black British (Black Caribbean, African, Other Black) and Chinese or Other Ethnic Group.
54,153,898 people (92.1 per cent of the population) ticked one of the 'White' categories, 2,331,423 (4.0 per cent) ticked 'Asian', 1,148,738 (2.0 per cent) ticked 'Black', 247,403 (0.4 per cent) 'Chinese', 677,117 (1.2 per cent) 'Mixed' and 230,615 people (0.4 per cent of the population) ticked the 'other ethnic group' box.
Since the UK Census relies on self-completion, the composition of the other ethnic group category is not fixed. Analysis by the Office for National Statistics of the 220,000 people in England and Wales who ticked the other ethnic group box in the 2001 Census reveals that 53 per cent were born in the Far East, 10 per cent in the UK, 10 per cent in the Middle East, and 7 per cent in Africa. People could write in an ethnic group under the 'other' heading. 26 per cent did not specify an ethnicity, but of the remainder, 23 per cent wrote Filipino, 21 per cent Japanese, 11 per cent Vietnamese, 11 per cent Arab, 6 per cent Middle Eastern and 4 per cent North African.
It is sometimes claimed that Census 2001 revealed that two-thirds of the population of Wales described themselves as of Welsh nationality. In fact, the 2001 census did not collect any information on nationality. Controversy surrounding the classification of ethnic group began as early as 2000, when it was revealed that respondents in Scotland and Northern Ireland would be able to check a box describing themselves as Scottish or Irish, an option not available for Welsh respondents. Prior to the Census, Plaid Cymru backed a petition calling for the inclusion of a Welsh tickbox and for the National Assembly of Wales to have primary law-making powers and its own National Statistics Office. With an absence of a Welsh tickbox, the only other tickbox available was "white-British", "Irish", or "other".
For the first time in a UK Census, those wishing to describe their ethnicity as Cornish were given their own code number (06) on the 2001 UK Census form, alongside those for people wishing to describe themselves as English, Welsh, Irish or Scottish. About 34,000 people in Cornwall and 3,500 people in the rest of the UK wrote on their census forms in 2001 that they considered their ethnic group to be Cornish. This represented nearly 7% of the population of Cornwall and is therefore a significant phenomenon. Although happy with this development, campaigners expressed reservations about the lack of publicity surrounding the issue, the lack of a clear tick-box for the Cornish option on the census and the need to deny being British in order to write "Cornish" in the field provided. The UK government has agreed recently that English and Welsh will have an ethnicity tick box on the Census 2011 but there will be no Cornish option tick box. Various Cornish organisations are campaigning for the inclusion of the Cornish tick box on the next census in 2011 .
On Sunday 29 April 2001 the United Kingdom Government held a census. This was the 19th UK Census. United Kingdom Census 2001 was started by the Office for National Statistics in England and Wales, the General Register Office for Scotland and the Northern Ireland Statistics and Research Agency. It was the first census to ask people in England, Scotland and Wales about their religion.