Hong Kong people once had full British nationality, including a British passport with the right of abode in Britain. But that right of abode was removed in 1962. [0]

The history is more complicated than most people think. As a child (early 90's) I had two friends from Hong Kong after a wave of immigration that started after Tiananmen.

[0] https://web.archive.org/web/20160424062259/http://www.taiwan...