BBC News | WALES | English and Welsh are races apart In April last year, research for a BBC programme on the Vikings revealed strong genetic links between the Welsh and Irish Celts and the Basques of northern Spain and south France.
It suggested a possible link between the Celts and Basques, dating back tens of thousands of years.
The UCL research into the more recent Anglo-Saxon period suggested a migration on a huge scale.
"It appears England is made up of an ethnic cleansing event from people coming across from the continent after the Romans left," he said.