Spot on. Only the BNP and UKIP are fascinated by ethnic purity and luckily they have a limited number of uneducated bigoted followers.
There was an interesting DNA study that I read on the BBC website some time ago about the Welsh (Celts of Breten) being 'true Britons' [1]
The Celts of Breten are the usually named as the true 'indigenous' Britons [2], but you wouldn't be able to find a 'pure' one if you tried. But the origins of the Celts are also suspected to be of mainland European descent as well. [3][4][5]
The real true Britons, who more than likely crossed the land bridge during the last ice age left no trace of themselves [6].
After the Celts the Saxons, Jutes, Angles, Danes, Romans and Normans were all additions to the melting pot. More recently, immigration after the WWII of workers from ex-Empire countries (now nearly all Commonwealth) have added to that vibrant mix.
1000 years later and our DNA is a good healthy mix. I think that was nature's design in the first place right?
[1] http://news.bbc.co.uk/2/hi/wales/2076470.stm
[2] http://en.wikipedia.org/wiki/Nick_Griffin#Policies_and_views
[3] http://en.wikipedia.org/wiki/Britons_(Celtic_people)
[4] http://en.wikipedia.org/wiki/Celts#Origins
[5] http://www.bbc.co.uk/history/ancient/british_prehistory/iron...
[6] http://www.bbc.co.uk/history/ancient/british_prehistory/peop...