Double Barrelled British

We seem to have strange nomenclature for some British people whose heritage isn't British.

For example, those in the UK of African heritage are predominantly from the Caribbean (although that's changing), despite them originally being from Africa, yet we call them Afro-Caribbean with no mention of the British part - why? They even self-identify as Afro-Caribbean. African-Americans are indeed originally from Africa and Americans. 

However, we don't refer to those in the UK of Scandinavian-Viking origin as Scandinavian-British, those of Saxon heritage as Saxon-British, those of Norman-French heritage as Norman-British, those of French Huguenot heritage as French-British, those of German heritage as German-British (except for the Royal Family when having a go at them) or those of Polish heritage as Polish-British. As soon as they learn to speak English they are considered assimilated.

When it comes to Asians we have Pakistani-British and Indian-British (although many white Brits refer to them solely as Pakistani or Indian, leaving out the British part completely), yet strangely those of Chinese heritage are still referred to as Chinese by almost everyone, despite - in many cases - having been in the UK for generations.

With the exception of those of Chinese heritage, it would seem we only have these double names for people who look different to the 'indigenous' population.

How long will it be before they're simply British? Probably never, as there's an obsession with visible difference. We could be kind and say the differences are due to continental separation of heritage, but let's not fool ourselves - it's visible difference that counts to the average person.