Britain has been a hub for sea travel ever since the land mass broke away from mainland Europe. Never in it's history has the UK had a completely closed imigration policy therefore I do not believe it is really possible to answer this question.
British... and I think just about every other nationality in some numbers. Supposedly the most multicutural city on Earth according to the stats
Probably hundreds, but in very small numbers.
193
193
There is about 198 different nationalities in the USA
The people who live in Great Britain have many nationalities which is a legal concept. Most have United Kingdom nationality.
45.
there are millions
Generally speaking, the English, Irish, Scottish and Welsh.
3
11 nationalities
VARIOUS
67
== The many different nationalities in the empire.===
No.
around 150 according to official statistics