Paddyanne they aren’t British citizens - they just have Overseas British passports which doesn’t give them the right of abode or the right to work in U.K.
I think it was probably a condition of the Sino-British agreement in 1997 (imposed by China) that they wouldn’t be given this right, because China would have ‘lost face’ if thousands of Chinese suddenly left Hongkong to live in UK.
Now that the Chinese have reneged on the agreement by passing this law, it has enabled the British Government to offer the right of abode & ultimately full citizenship to these people.
Having lived & worked in HK for 11 years, I’m very glad that our Government is doing the right thing, and I’m sure any HK residents who come here to live and work will be an asset to our country.