A grandmother who was told she was an illegal immigrant, detained in an immigration removal centre and threatened with deportation despite having lived in Britain for 50 years has finally received official leave to remain in the UK.

Paulette Wilson, 61, a former cook who served food to MPs in the House of Commons, has been denied benefits and access to healthcare and refused permission to work for the past two and a half years. After a week in Yarl’s Wood immigration detention centre in October, she was taken to Heathrow for deportation to Jamaica, a country she had not visited since she left at the age of 10 and where she has no surviving relatives.

Coverage of her situation in the Guardian last month prompted anger among politicians and readers. This week she received a biometric residency permit, confirming her settled status in the UK and bringing her a step nearer to gaining British citizenship.

“It’s great news. I’ve been really struggling for the last two and a half years – it’s hard without money,” Wilson said. She remains puzzled by why she was told she was an illegal immigrant, when she had worked and paid taxes in the UK for most of her life.

“I’ve never done anything wrong; how could I be an illegal? It would be nice to get an apology from the government saying: we are sorry we put you though this.”

Wilson’s daughter, Natalie Barnes, said her mother now had to complete a naturalisation process to become a British citizen. Barnes added that, despite her relief, Wilson was still traumatised by her experience.

“The experience of being in the detention centre won’t ever leave her,” Barnes said. Barnes had repeatedly tried to explain to Home Office staff in Solihull that her mother was not an illegal immigrant, but was banned from the building because staff were annoyed at her persistent attempts to tell them they had made a mistake.

An intervention by Jim Wilson, a lawyer who works with the Refugee and Migrant Centre in Wolverhampton, helped prevent Paulette’s deportation to Jamaica. He said her papers had come through unusually quickly once the case was highlighted in the media.

Paulette Wilson with her daughter, Natalie Barnes. Photograph: Fabio De Paola/The Guardian

“She has been treated abominably,” he said. “It is significant that they picked on a vulnerable person – someone who can’t read properly, who has no knowledge of the system and no funds to get legal advice. There are plenty of other people in this situation, we just don’t know how many.”

Wilson’s MP, Emma Reynolds, said: “This is not an isolated case and I have asked the Home Office to assess how many people in Paulette’s situation are being treated in this appalling way.”

The case has helped to expose the Home Office’s harsh treatment of a number of long-settled, retirement-age UK residents, who are being aggressively pursued over their immigration status. Most were unaware that their papers were not in order until Theresa May’s announcement of a “hostile environment” for immigrants in 2012.

Publicity around Wilson’s situation has prompted several other people, who have lived in the UK for more than half a century before encountering similar difficulties, to come forward. John Clarke, 71, came to England from Saint Vincent in 1962, when he was 15, and has lived and worked here ever since, bringing up two children. He has been trying to renew his passport since 1988, without success.

His application for British citizenship was refused again earlier this month. He had hoped to marry two years ago, but had to cancel the wedding because he had no papers. He wants to visit his sister in the Netherlands because she is very ill, but has not been able to travel, despite spending more than £1,600 on trying to get a passport.

Clarke had been under the impression that he was a British citizen, since he has lived here continuously since 1962.

His MP, Chris Heaton-Harris, said: “I am in regular conversation with Home Office officials to try and get this unfortunate matter resolved. I understand the stress this has caused John and I sincerely hope we are able to find a solution shortly.”

A Home Office spokesperson said: “Mr Clarke applied for British ctizenship but unfortunately does not qualify under nationality law. We have contacted Mr Clarke to advise him on how he can regularise his stay here.”