Brexit is already deepening inequalities among British nationals in France, with some losing rights due to varying levels of Brexit preparedness among local authorities, and the less well off, women and people in poor health disproportionately affected, research shows.

Extensive interviews with more than 100 British residents in France as part of the 18-month BrExpats programme at Goldsmiths, University of London, have revealed widely differing individual outcomes, Michaela Benson, the project lead, said.

With the UK now sure to leave the EU on 31 January, France requires all British residents to have applied for a carte de séjour, or residence permit, by July 2021. However, Brexit uncertainty has until very recently caused major confusion.

Responsibility for migration governance has been devolved to local government level in France, and central government communication has not always been effective, leading to British residents receiving very different treatment.

“Not only have British nationals been confused, but on many occasions, they have been faced with French officials who have also been confused,” Benson said.

Many local government officers in France were reluctant to process British citizens until relatively recently, dissuading people from even applying until 12 months ago, and Britons are encountering a range of administrative problems even now, she said.

One woman considering a civil partnership with her Irish partner was described by an official in the local mayor’s office as “foreign”, depriving her of rights that, in law, her EU citizenship still permitted.

Such problems are deepening inequalities among British citizens in France, which has the second largest population of UK nationals in Europe after Spain, causing greater uncertainty, insecurity and instability for those who are less well off and for women and people in poor health, the research reveals.

“In a context of declining resources and chronic health conditions, these problems can be just one thing too much,” Benson said. “Brexit is revealing faultlines within the British population irrespective of their legal status.”

Continued access to healthcare was paramount for several interviewees, particularly those managing chronic conditions. Benson described the case of a 70-year-old widow living on a UK state pension, working to make ends meet and with no capital to fall back on.

“Her house was run-down, she could not afford to go back to Britain to visit her family, and she would have no quality of life in Britain if she returned,” she said. “She does not have the luxury of dwelling on the possible routes she might take to secure her future; she is focused on living from one day to the next.”

Some residents are so fearful of being told to leave, particularly because they worry they might not meet a post-Brexit income threshold, that they are avoiding contact with the French authorities altogether, she said.

“Only time will tell who falls between the gaps,” Benson said. “But what is clear is that some, with the right level of resources and the confidence to question things, will be fine. Others will be cast aside as less ‘deserving’.”