When Aziz Isa Elkun learned of his 78-year-old father’s death in 2017, he rushed to ring his mother from his home in north London. As usual, they weren’t able to speak for long.

For years, local police in China harassed his family every time he called. So that day, when she said, “It’s a bit difficult to talk at the moment,” he knew it was time to hang up. 

The next time he rang the number wasn’t available. By the start of this year, calls to his mother, Hepizem Nizamidin, 76, wouldn’t even connect.

“It’s been two years – no news, no anything. I’m afraid to think about my mother. What’s her situation now?” said Mr Isa Elkun, a poet. “I try not to think too much negatively. But it’s difficult…