From Wellcome, the University of Oxford, and UCL, the first fine-scale genetic map of the British Isles. This definitely settles some long-standing debates and also bolsters common folk understandings of boundaries…
* “the Anglo-Saxons intermarried with, rather than replaced, the existing populations”.
* “there is no obvious genetic signature of the Danish Vikings” — and even up in Orkney the Norwegian Vikings are only at 25% of the DNA, which is congruent with raiding rather than robust over-wintered settlement. Very interesting, and perhaps the most unusual finding. Perhaps a strict Danish Viking religious prohibition on siring inter-bred children could explain this?
* “a substantial migration across the channel after the original post-ice-age settlers, but before Roman times.” So the pre-Roman Gauls and Belgics (or their ancestors) did indeed press across the Channel and somewhat up into southern England, displacing the south-coast natives over to London in the east and Cornwall in the west. That would explain “why the Cornish are much more similar genetically to other English groups than they are to the Welsh or the Scots.”
* there’s no discoverable Roman genetic presence, or their legionnaires or slaves.
* “The Welsh appear more similar to the earliest settlers of Britain after the last ice age than do other people in the UK.” That fits with other genetic studies from 2006/7, which found that the Celts had started moving north from the Basque country to colonise all along the Atlantic coast as far north as Ireland and western Scotland, a migration completed into Ireland circa 1,700 BC. But the new Wellcome study appears to show that the Celts never fully penetrated the difficult terrain of inland Wales, even once they were settled in the British Isles.
* English areas maintained their “regional identity for many centuries”, and many broadly map onto the old English counties and onto long-standing regional grassroots understandings of boundaries. Cumbria vs. Yorkshire, Devon vs. Cornwall are sharply distinct genetic regions.
The report can offer no indication of where the Mercian Anglians may have come from, or who they really were on the continent (Vandals, Goths, Frisians?), so far as I can see. Continental DNA sampling is apparently patchy at present, and the study didn’t look at the Netherlands (where Ghent was a Vandal city, for instance).
Study papers: People of the British Isles.