This is the Religion data (KS206) from the 2011 Census. The data provides the religion of all usual residents.
The question was:
What is your religion? (this question is voluntary)
Christian (including Church of England, Catholic, Protestant, and all other Christian denominations)
Any other religion, write in
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