This is the Ethnic Group data (KS201) from the 2011 Census. The data provides the ethnic group of usual residents.
The question was:
What is your ethnic group?
White: English/Welsh/Scottish/Northern Irish/British
White: Gypsy or Irish Traveller
White: Other White
Mixed/multiple ethnic groups: White and Black Caribbean
Mixed/multiple ethnic groups: White and Black African
Mixed/multiple ethnic groups: White and Asian
Mixed/multiple ethnic groups: Other Mixed
Asian/Asian British: Indian
Asian/Asian British: Pakistani
Asian/Asian British: Bangladeshi
Asian/Asian British: Chinese
Asian/Asian British: Other Asian
Black/African/Caribbean/Black British: African
Black/African/Caribbean/Black British: Caribbean
Black/African/Caribbean/Black British: Other Black
Other ethnic group: Arab
Other ethnic group: Any other ethnic group
The 2011 census in England and Wales took place on 27th March 2011. It provides a snapshot of the population and its characteristics on that day.
Further information about the census estimates, including details about the methodology is available here: http://www.ons.gov.uk/ons/guide-method/census/2011/index.html