The UK Border Agency records details of the number of individuals arrested as suspected immigration offenders, details of prosecutions, and the details of those removed on three separate systems. In order to achieve the required level of data quality, the cross-referencing of data between the three systems could be completed only by the detailed examination of individual case records at disproportionate cost.
The Home Office publishes statistics on the number of persons removed and departed voluntarily from the UK on a quarterly and annual basis, as well as statistics on persons proceeded against for offences under Immigration Acts in England and Wales annually. National Statistics on immigration and asylum are placed in the Library of the House and are available from the Home Office’s Research, Development and Statistics website at:
http://www.homeoffice.gov.uk/rds/immigration-asylum-stats.html