Simon Cheng still visibly tenses when he describes his detention in China. In 2019, Cheng, a pro-democracy activist from Hong Kong and a former employee of Britain’s consulate there, was arrested after a business trip to mainland China.

For 15 days, he was questioned and tortured, according to his account. Beijing confirmed his detention but denied he was mistreated. When he was finally released, he no longer felt safe in Hong Kong, and in early 2020, he fled to Britain and claimed asylum.

"It’s not hard to adapt to a new life in the U.K. in some ways," said Cheng, 33. "But also, I can’t move on from the fate of my home city."