The nationality of HongKonger was the same as other UK citizen at the time called CUKC. For other UK ex-colony, they usually had a independent election to be an independent country or so, and these countries do not have the UK nationality anymore. But HKers never had such election taken place.
> China's leaders explicitly wanted to "preserve the colonial status of Hong Kong".[21] Liao Chengzhi, a senior Chinese official in charge of Hong Kong affairs, said in 1960 that China "shall not hesitate to take positive action to have Hong Kong, Kowloon and New Territories liberated" should the status quo (i.e. colonial administration) be changed. The warning killed any democratic development for the next three decades.
https://en.m.wikipedia.org/wiki/Democratic_development_in_Ho...
http://www.nytimes.com/2014/10/28/world/asia/china-began-pus...