However, there's no such country as Britain.
England + Wales are one unit for personal law/domicile/legal systems.
ADD Scotland, and you get Great Britain.
ADD Northern Ireland [NOT "ULSTER"- that ms 8 counties, not 6] and you get the United Kingdom.
ADD Channel Islands + Isle of Man and you get the British Isles. The UK has responsibility for the extrernal affairs of the islands but they are full self-governing internally.
And Gibraltar? Well, although it's a colony, it counts as part of SW England for EU voting purposes- until the happy day that the UK sees sense and leaves the EU for freedom outside it...
And Gibraltar? Well, it's a colony- but it's added to SW England