[Englegast]

Almost all previous anglo-saxon settlements became "England", "the land of Engles or Angles" and the rest of the isle retained most of their indigenous population.
Of course there is something called genetic drift and population movements and as such over the course of the centuries the other regions received anglo-saxon input and England more indigenous input.

Have you seen these studies carried out on the y-chromosone?

http://www.bbc.co.uk/history/program...sults_01.shtml
http://news.bbc.co.uk/1/hi/wales/2076470.stm
http://www.gnxp.com/MT2/archives/000648.html
http://www.ucl.ac.uk/tcga/tcgapdf/Weale-MBE-02-AS.pdf
http://mbe.oxfordjournals.org/cgi/co...full/19/7/1008