Undocumented Migrants
2026-06-29 · Home Office · 14511 · Official question
Question
To ask the Secretary of State for the Home Department, what methodology was used to estimate the figure of 412,000 illegal migrants in the United Kingdom.
Answer
The figure was derived from a review of Home Office case working systems and includes individuals who are believed to be in the UK and do not have valid leave recorded. The figure also includes foreign nationals who hold valid leave but are being consider...