My parents never had right of abode. I asked my dad, and he said that the laws were different then, and even after seven years, he wasn't allowed to apply for it. He wasn't 100% on it, but that's how he remembers it. He came to HK on a work visa and continually extended it, until they gave him unconditional stay.
I am still going to try, because UK/HKboy if you say they do it on a case by case basis, then I guess I have nothing to lose. And my identity card and birth certificate must surely stand for something?! It's weird, because in a way, I feel like I have become 'stateless'. I have no affinity towards South Africa, and I don't have right of Abode in Hong Kong.
I really love and miss HK, but I have a feeling you're right Aritaurus: the next time I visit it will have to be on a tourist visa, which is going to be really strange for me.