The Government Says

Welcome: a guide for Hong Kong British National (Overseas) visa holders in the UK

Welcome: a guide for Hong Kong British National (Overseas) visa holders in the UK
Local copy of Hong_Kong_BN_O__welcome_pack.pdf

https://www.gov.uk/guidance/welcome-a-guide-for-hong-kong-british-national-overseas-visa-holders-in-the-uk

seen at 00:01, 8 April in Search.