The hostile environment confuses unlawful with undocumented, with disastrous consequences (Migration Mobilities Bristol, link):
“In reality, Home Office data on the immigration status of residents of the United Kingdom is often wrong and this has become increasingly clear in the years following Theresa May’s announcement in 2012 of her intention to make Britain a ‘really hostile environment for illegal immigrants‘. Public confirmation was provided as early as 2013 after a contract was awarded to the private company Capita to track down 174,000 suspected unlawful residents on the Home Office database. As soon as the company started sending out threatening text messages, though, it became clear that lawful residents and even British citizens were somehow on the database (Dixon, 2018). In 2016 it emerged that hostile environment bank account checks were throwing up incorrect results as much as 10% of the time (Bolt, 2016). In these cases, people were wrongly being refused permission to open a bank account. Officials admitted that relevant changes to a person’s status might not be entered on the relevant database ‘until some months after the event, and that data was often entered in the wrong field, commonly as free text.’”