By the year 410 all the Romans had fucked off to defend their country which was being invaded by the mongols, from AD 50ish those same Romans thought it was a good idea to conquer this land of ours as it was the last part of the known world, we as a race were Britons and had our own religion, language, farming, road system the works, but they thought we needed their help, or someone invited them to come over as there was alot of infighting amongst local tribes.
So up until 410 there would have been alot of kissing and canoodleing going off with our local females, hence alot of inter breeding.
From 410 to 580ish(know as the dark ages)there is not alot of writen history, but life went on, from 580ish that's when the Anglo-Saxons came to the fore, again inter breeding, then it was the turn of the vikings same again.
Then 7000 normans(with a mix of jonny foreinger)came over in 1066 and subjugated around 1.5 million locals, still more of the local shagging went off.
In between we had the "Danelaw" where the country was plit diagonally from west to east,so basically we have had around 1000 years of immigrants coming to these shores of ours before 1066.
I am 100% English love my country to death, I was born here, but a little of me belongs to the master race(mother Austrian )
So sorry to say there is no purity where England is concerned.
PS do you know where the word English comes from.....I do