According to former Home Office chief David Wood, more than one million immigrants are currently living in Britain without a UK visa “under the radar”.
Mr Wood, who worked as head of UK immigration enforcement until 2015, told MPs at the beginning of the month that these illegal immigrants include those who have overstayed their UK visas, criminals who have escaped deportation and failed asylum seekers.
Speaking at the Commons home affairs committee, Mr Wood said: “There are probably over a million foreigners here illegally at the moment. There’s a large number, so no one could ever remove them really.”
Campaigners have suggested that many of these people are unlikely to be sent home, and instead could put additional pressure on Britain’s schools, health service and housing system.
Mr Wood also stated that Brexit could result in an increase in the number of illegal immigrants overlooked by the system as UK immigration departments are likely to focus their energy on easy-to-remove EU nationals overstaying their UK visas.
Commenting on Mr Wood’s statement, member of the home affairs committee Tim Loughton suggested that his figures highlights weak points in the UK immigration process that need to be tackled as soon as possible.
He added: “It does raise questions about the ability of the department to make sure we have a watertight immigration system in place to deal with people who are not supposed to be here, especially post-Brexit.”