Were they subject to immigration controls?
Who are the Windrush generation?
Labour have pointed to changes to United Kingdom immigration law introduced while the Prime Minister herself was in charge of the Home Office. In 2012, May described the measures as designed to create a "hostile environment" for people who were in the United Kingdom illegally. As a effect, some lost their jobs, others were evicted from their homes, and a few were reported to have been threatened with deportation.
Downing Street has rejected a meeting on the Commonwealth-born residents' immigration issues, but have been opposed by 140 MPs from across the political spectrum.
Downing Street had refused a request from the high commissioners of 12 Caribbean nations for a meeting as it emerged that large numbers of people were being threatened with deportation, denied access to healthcare, lost jobs or been made homeless because they do not have sufficient paperwork to prove they have the right to be in the UK.
Stung by a wave of negative publicity, the government backed down and said a meeting would take place.
Answering questions in the House of Commons later, Home Secretary Amber Rudd vowed to "find out if there are any such people who have been removed".
Glenda Caesar was just six months old in 1961 when she traveled from Dominica to the United Kingdom with her parents.
This has meant that people who are now either pensioners or are approaching that age, and who have spent their working lives paying taxes in the United Kingdom and often working in public services such as the National Health Service or in the general infrastructure of the country, raising children who are legally resident, are now facing uncertainty. "I am not working at present and still need documentation on my father and school or medical records as the final part". "They find themselves abandoned and made destitute by a country they have given their lives to", he told Sky News on Monday.
Meanwhile, a petition on the government's website calling on the Home Office to grant them an amnesty has attracted the 100,000 signatures required to be considered for a debate in Parliament.
"It's like telling the descendants of fourth generation Irish immigrants to the U.S. that suddenly you might not be American after all and could be deported", Vernon told CNN.
It said: "We urge you to guarantee the status of all Commonwealth nationals whose right to remain is protected by law and to provide an effective, humane route to the clarification of their status".
"She is aware that many people are unlikely to have documents that are over 40 years old and she is clear that no-one with the right to be here will be made to leave".
"This should not happen to people who have been longstanding pillars of our community", he said.
However, the Home Office did not keep a record of those granted leave to remain or issue any paperwork confirming it, meaning it is hard for the individuals to now prove they are in the United Kingdom legally.
She told Channel 4 News: "Potentially they have been and I'm very conscious that it's very much in error, and that's an error that I want to put right".