Britain and Ireland are so thoroughly divided in their histories that there is no single word to refer to the inhabitants of both islands. Historians teach that they are mostly descended from different peoples: the Irish from the Celts, and the English from the Anglo-Saxons who invaded from northern Europe and drove the Celts to the country’s western and northern fringes.
iht.com/articles/2007/03/05/news/web.0305BRITS.full.php