Nicholas Soames: To ask the Minister for the Cabinet Office what account the census will take of the illegal immigrant population. [117431]

Nick Hurd MP; Parliamentary Secretary: The information requested falls within the responsibility of the UK Statistics Authority. I have asked the authority to reply.

Letter from Stephen Penneck, dated July 2012:

As Director General for the Office for National Statistics (ONS) which has responsibility for the Census, I have been asked to reply to your recent question to the Minister for the Cabinet Office asking what account the census will take of the illegal immigrant population (117431).

The Office for National Statistics mailed out 2011 census questionnaires to all residential address using an address list compiled from other national sources such as the Royal Mail, Ordnance Survey and the National Land and Property Gazetteer. Thus most, if not all, residential properties, including those containing immigrant households, will have been counted in the 2011 Census. Indeed the Census is the only nationally consistent source of the number of immigrants and their families in the country at the local area level.

One of the main purposes of the Census is to identify the level of need for different services within the community, and this applies as much to immigrants as to other sections of the population. Particular attention was given in the 2011 Census to developing a community liaison programme to ensure that all immigrant communities were aware of the census and their statutory obligation to complete a census questionnaire. We recognised at the time, however, that, despite this statutory obligation some people may not have wished to make themselves known to us, and so we worked closely with local community organisations to make particular efforts to tell people that the information they give in the census would be treated as strictly confidential and would not be shared with anyone else.

However, we are able to estimate the numbers and characteristics of persons who were missed in the census by undertaking a separate and independent Census Coverage Survey, and the estimates of population and households published in the first release of statistics from the 2011 Census on 16 July takes account of these. Of .course, the census did not include a specific question about legal immigrant status, so we will not be able provide any statistics, from census information, that would distinguish between legal and illegal immigrants.