London: Margaret O’Brien, 69, moved from Canada to Wolverhampton in 1971, got married, had three children and worked for the local council for more than 25 years variously as a dinner lady, meals on wheels driver, lollipop lady and cleaner.

A spinal injury a few years ago meant she had to give up her job, leading O’Brien to apply for benefits for the first time. In 2015, she was told her disability payments had been suspended because she was an illegal immigrant.

O’Brien received a letter stating: “Home Office records indicate that you do not have permission to be in the UK. You should make arrangements to leave without delay.”

The letter informed her “of our intention to remove you from the UK to your country of nationality if you do not depart voluntarily. No further notice will be given”.

If she decided to stay, the letter warned, “life in the UK will become increasingly difficult”; O’Brien was liable to be arrested, prosecuted and face a possible six-month prison sentence.

Her case is significant because it shows the Home Office’s treatment of long-standing Commonwealth-born UK residents is not restricted to the Windrush generation, but is likely to extend to people from other Commonwealth countries.

The letter arrived a few days after her son’s wedding. “I tried to call the telephone number provided, but it was absolutely impossible to get through. My son was on honeymoon in New York. I didn’t know what to do,” she said. O’Brien sought legal advice, but she was told it would cost GBP900 for initial work. “I’m a disabled pensioner. I didn’t have that kind of money,” she said.

Not long afterwards, she was issued with a letter headed “notification to a person who is liable to be detained”. Her photo was above the words: “You are a person without leave who has been served with a notice of liability to removal.”

She gathered a large number of documents as evidence that she had lived in the UK before the 1973 Immigration Act was passed, and was in the country legally. After more than a year of trying to convince officials, she was allowed to meet a Home Office decision-maker in person. She was ready to show him her documents, but he simply asked her if there was anyone in Canada who could house her.

“I don’t know whether they get brownie points for the number of people they can send back to their own country,” O’Brien said. She had the feeling he was looking at her and thinking: “Is this someone I can take in?”

O’Brien’s account stands out as shocking even among the deluge of revelations about Home Office behaviour. But she said two years of getting by without disability benefit is nothing compared with stories of detention and forced exile in Jamaica. “I was humiliated, but there are so many people in situations much worse than mine,” she said.

She found the requirement to report every three months at the Home Office very difficult because of her disability. O’Brien walks with a frame and has to be accompanied by someone when she goes out, because she has a health condition that makes her prone to collapsing unexpectedly.

The 25-mile journey via bus, train and tram to the Home Office reporting centre in Solihull takes about two hours each way. On one occasion, she arrived only to be told the office was closed for a training day; on another, she queued for more than two hours before being asked to come back another day.

The waiting room was like a cattle market, she said, crammed with about 200 people, among them babies — and sometimes adults — crying. People branded overstayers, illegal immigrants or refused asylum seekers had to hand over all sharp objects, pens, pencils and keys, as well as mobile phones, at the door. Chairs were screwed to the floor.

“It was very degrading. I’m a disabled woman. Sometimes, I was in a lot of pain,” O’Brien said. It cost about GBP40 each time in travel costs for herself and her grandson or one of her children. “I thought: fine, I will just explain my situation. You hope miracles will happen and someone will just listen to you,” she said.

Her daughter, who was not allowed in and had to wait outside, once saw a group of people being bundled into a van — presumably to be detained. After that, both of them feared she might be next. The security guards on the door were always kind to her; she thought they felt sorry for her because she was finding it physically difficult to make her way to the office.

“They told me: you shouldn’t be here,” O’Brien said. Inside the building, Home Office staff were less friendly. “To them, it is just a job. Maybe they have to meet numbers, meet a certain number of people a day. You’re just treated as a number,” she said.

O’Brien had first been informed that she had a problem with her paperwork when the council pointed out in about 2008 that her Canadian passport had expired, and asked her for an alternative document.

She had never applied for a British passport and was not planning a holiday, so decided to explain to council staff that she had been in the UK for decades and did not need to prove a right to reside. This was several years before the introduction of the “hostile environment” policy, and staff immediately let the matter drop.