A charity that has fought hard to dismantle the government's 'hostile environment' policy is asking immigration solicitors for help to map the UK's undocumented migrant population ahead of Brexit.

The Joint Council for the Welfare of Immigrants (JCWI) wants to collect data to inform a project exploring simpler, cheaper and better routes for migrants seeking to regularise their status in the UK.

The charity told the Gazette that a 'perfect storm' is approaching: the end of freedom of movement, the risk of tens of thousands of people losing their status under the EU settled status scheme, and the 'ramping up and digitisation' of the government's hostile environment policy.

JCWI said: 'For our campaign to really achieve the impact we'd like, we need a rock solid understanding of the undocumented population. No one knows better than immigration lawyers the complexity and narrowness of existing routes to documentation, and we rely on that expertise to make sure we have a complete picture from all across the country of what our campaign should look like and prioritise.

'We need as many lawyers as possible to take the time to respond to our survey, and help us build the strongest possible campaign for a fairer, simpler, safer system.'

A briefing published by the charity earlier this year states that around four million people resident in the UK before the end of the Brexit transition period will need to apply for settled status under a new application process.

JCWI says the settled status scheme creates 'arbitrary cliff-edges', which could result in those who have failed to obtain status becoming undocumented overnight. Home Office targets for processing applications are 'ambitious' but the charity questions whether staffing and training provisions are sufficient. EU nationals may also find themselves ineligible to apply due to poor decision-making or being subject to a wrongful removal or deportation order.

The charity's Routes to Regularisation Research survey can be found here.