I personally don't like how black ethnic groups are broken down in the UK. I get the Black Caribbean, Black African and Black Other but it's lazy. South Asians get their distinct countries and ethnicities. They need to break it down further by countries and ethnicity.
Examples:
Black Caribbean then jot down what country and ethnicity, such as Jamaican, Barbadian, Trini, St Lucian, etc.
Black African then jot down what country and ethnicity, such as Nigerian, Ghanaian, Kenyan, Zimbabwean, Congolese, etc.