Written question asked by David Davis (Conservative) on Wednesday, 29 June 2005, in the House of Commons. It was due for an answer on Monday, 4 July 2005. It was answered by Charles Clarke (Labour) on Tuesday, 19 July 2005 on behalf of the Home Office.

Illegal Immigrants

Question: To ask the Secretary of State for the Home Department if he will estimate the number of illegal immigrants living in the UK.

Answer: No Government has ever been able to produce an accurate figure for the number of people who are in the country illegally. By its very nature it is impossible to quantify accurately, and that remains the case.Although it is impossible to determine accurately how many people are in the UK illegally the Home Office published a report which included an estimate of the size of the illegal migrant population in the UK in 2001. It should be noted that the report included an estimate, not an accurate or definitive figure.As mentioned in the report the only method to estimate the size of the unauthorised migrant population in the UK that currently can sensibly be applied is the residual method. As the method relies on data from the census of the population undertaken every 10 years, it is not possible to produce an estimate for a more recent year.A copy of the Research, Development and Statistics On-line report 29/05—““Sizing the unauthorised (illegal) migrant population in the United Kingdom in 2001”” can be found at: http://www.homeoffice.gov.uk/rds/notes/june_summaries.html.

Secondary information