Towards the end of last year, Pål Hansen walked down to his local allotment, not to plant vegetables, but to bury several sheets of photographic film. Digging a hole, he carefully placed the film in the damp Hackney soil, patted it down and went home.

A few days later the Norwegian-born photographer returned to reap his unconventional harvest. Retrieving the sodden colour film from the ground, he returned to work on it in his studio. The faces that emerged through the patina of the damaged and degraded emulsion were all victims of the Windrush scandal, first reported by Guardian journalist Amelia Gentleman in 2017.

Anthony Bryan, 60, came to the UK in 1969, aged 10, and was educated in London before becoming a painter and decorator. In 2015 he applied for a British passport in order to visit his mother in Jamaica and was informed he had no right to remain in this country. Since then, he has lost his job and twice been locked up in detention centres. ‘The first was actually a prison with barbed wire all around. It was terrifying.’ In June 2018, the Home Office offered him an apology after it was concluded the department had displayed an ‘inadequate regard’ for his human rights. Photograph: Pål Hansen/The Observer

Hansen, appalled by the government’s targeting of Commonwealth nationals living in the UK, had contacted his subjects through the various organisations that have acted on the victims’ behalf, including Praxis, the Joint Council for the Welfare of Immigrants, LRMN and IMiX. After meeting to hear how their lives had been ruined by mental distress, debt and the threat of deportation, he photographed them at their homes before taking the trip to the allotment.

By burying the film, Hansen wanted to root the subjects in British soil, to fix them back in the country where they have lived for most of their lives. “I love Britain and I was proud of living in a place that could make all these cultures work together,” says the photographer, who moved to the UK as a student in 1996. “The government’s treatment of immigrants hasn’t affected me personally, but I felt I had been lied to as well.”

Eleanor Petersen, 60, was born in the US Virgin Islands, Eleanor came to the UK in 1966 to join her mother who was a nurse in Leeds. She moved to London as an adult, working in customer services until 2015. That year, she renewed her American passport, only for the Home Office to refuse to transfer her indefinite leave to remain stamp. ‘I wasn’t able to work as no company could accept me. It was an Orwellian nightmare.’ Photograph: Pål Hansen/The Observer

Hansen’s blemished prints evoke the blighted lives of his Windrush subjects. Obscured, almost spectral, they inhabit a hostile environment. These are identities in crisis. “Each image is starting to erode and disappear, so that in itself is a symbol of what the government is trying to do to them – erase them from history.”

The 46-year-old is known for his editorial assignments, including portraits for the Observer, and for shooting anti-fur and pro-vegan campaigns for Peta. For his Windrush series he changed tack, ditching his fast-paced digital work in favour of a Victorian-style large-format camera, complete with tripod and dark cloth, which typically requires a more thoughtful approach.

Sylvester Marshall, 63, a former mechanic, became the first Windrush case to attract political attention in 2017 when the NHS refused him radiotherapy for prostate cancer as he couldn’t prove his legal status. Soon afterwards he was evicted from his hostel in London and forced to sleep on the streets after failing to convince officials he was not an illegal immigrant. ‘I was telling them all the way I am British, but they just wouldn’t have it,’ says Sylvester, who arrived in the UK as a teenager in 1973 to join his mother, an NHS nurse. ‘Being rejected like that was terrible. It made me feel like a lost sheep.’ He was finally granted the right to remain in the UK last year. Photograph: Pål Hansen/The Observer

“Many of the people in the portraits felt a sense of shame at not being accepted by Britain, so I wanted to take the images in a way that is empowering. The stillness of each composition gives a feeling of pride. Also, the analogue process is quite costly – every frame counts – so that allowed me to give a sense of value back to the subjects.”

All of Hansen’s personal projects exhibit the same compassionate curiosity. Previously he’s taken portraits of tabloid-stigmatised teenage parents, and commemorated the youth activists massacred by Anders Breivik in 2011 by retracing the extremist’s car journey from Oslo to Utoya in a series of distorted, searing CCTV-like images.

It’s about giving people a voice, says Hansen. “Most of the people in the Windrush portraits are in their 60s now and have been made to feel as if they’ve served their purpose and no longer have any use in this society. They have ended up in this empty space.”