THOUSANDS of Europeans living in the UK, including a high number of Spaniards, could lose their basic rights following Brexit – and children, the elderly and victims of domestic violence are the most at risk, says the Migration Observatory at Oxford University.

Even if they meet all the requirements for remaining permanently in Britain once the country leaves the European Union, problems in presenting the required paperwork to obtain 'settled status' could leave them in a situation similar to that of an 'illegal' immigrant and losing their right to stay.

The Observatory's report warns that thousands of Europeans in the UK may not understand that they need to go through this paper trail, meaning they would lose their residence rights without even realising and discover their situation when it is too late.

“The Interior Ministry is attempting to create a system whi9ch is easy and direct, and the majority of European citizens should be able to get through this simplified process with few problems,” the Migration Observatory's director Madeleine Sumption says.

“But for a minority of people, the process will be much harder.”

She cites those who are 'socially isolated', victims of 'exploitation', and 'personal barriers' such as poverty or mental illness.

Also, parents of the tens of thousands of children born in the UK mistakenly believe, in most cases, that their kids are automatically considered as having 'settled status' and enjoying the same rights as a British child.

This means the parents may not apply for residence on behalf of their children, who could, in theory, be 'deported'.

Another group at serious risk are the 140,000 or so Europeans who have lived in the UK for over 30 years, and the 56,000 EU nationals there aged over 75.

They include numerous Spaniards, principally from the Basque Country, in their 80s or 90s who were evacuated to Britain during the Civil War and stayed there, as well as dissenters who fled to the UK during Franco's régime or who moved there to find work during times of extreme poverty in Spain.

Those who have been in Britain for most or all of their adult lives may already hold documents which accredit their 'permanent right to remain', and believe that as a result, they do not have to apply for 'settled status' – whereas, in fact, they do, or they will be considered 'illegal immigrants'.

Europeans in 'particularly vulnerable' situations, Madeleine Sumption says, could also fall foul of Brexit – victims of domestic violence, including psychological abuse and excessive control, may be in a situation where they rely on their partners to deal with their paperwork, or may be prevented from leaving the house or using the internet to do so themselves.

Britain's Interior Ministry plans to open the 'settled status' process this year so that the more than three million EU citizens living in the country can register, allowing them to keep their residence rights and work permits.

Only those who have lived in the UK for five years or more by the end of the year 2020, when the Brexit 'transition period' expires, can apply for 'settled status'.

Anyone who has not lived there long enough by this date can remain in the UK until they have acquired five years of continous residence, then they will be required to apply for 'settled status'.

Brexit will formally take place on March 29, 2019, but during the transition period, the UK will remain subject to EU rules and to the benefits of the single market, albeit without any decision-making power.

Photograph by campaign group Bremain in Spain, led by Sue Wilson, at an anti-Brexit protest march in Manchester