The UK government is facing increasing scrutiny over its failure to produce updated estimates on the country’s illegal migrant population, with the last official Home Office estimate dating back to 2005. According to an in-depth report by The Times, UK, the lack of recent data has led to uncertainty around the true scale of irregular migration, which some experts estimate could now exceed 1.2 million people.
The Home Office’s 2005 study, based on the 2001 census, estimated the illegal migrant population to be between 310,000 and 570,000. However, the government has not conducted further research since then, citing the complexity of defining and tracking unauthorised migrants. Experts highlight four main pathways to illegal status: overstaying visas, entering with forged documents, failing to leave after asylum rejection, and being born to undocumented parents.
Recent unofficial research by universities, think tanks, and the Greater London Authority (GLA) suggests a far higher figure. A 2020 GLA study estimated 674,000 undocumented migrants in the UK, with nearly 60% residing in London. Further analysis by the Pew Research Centre in 2019 ranked the UK as having the second-largest unauthorised migrant population in Europe, after Germany.
The challenge of tracking illegal migration has been exacerbated by unlinked government databases across departments, including HMRC, the Department of Work and Pensions, and the DVLA. Critics argue that the lack of a coordinated data system leaves authorities unable to enforce immigration policies effectively.
Compounding the issue, small boat crossings across the English Channel have surged in recent years. According to The Times, arrivals increased from just 299 in 2018 to a record 45,774 in 2022. While numbers dipped slightly in 2023, crossings in early 2024 indicate a continued rise in irregular migration.
Former Immigration Enforcement Director General David Wood estimated in 2019 that 150,000 people per year were becoming illegal migrants, largely due to visa overstays. The last Home Office data from 2020 showed 91,612 visa overstayers, with visitor visas accounting for the largest share. However, the government has since ceased publishing such statistics, raising concerns about transparency.
The UK’s immigration policies have also come under fire for their unintended consequences. The Conservative government’s “hostile environment” policies, introduced by former Prime Minister Theresa May, were designed to deter illegal migration but instead pushed many undocumented individuals further underground. The Windrush scandal, which saw British citizens of Caribbean heritage wrongly deported, further undermined confidence in the government’s handling of immigration enforcement.
As pressure mounts for updated data and clearer policies, campaigners and researchers continue to call for a more humane approach to regularisation, particularly for young undocumented migrants. Meanwhile, with migration set to remain a key political issue in the upcoming general election, the government faces tough questions on its ability to address the growing crisis.
