The 20th-century historian Frank Stenton wrote that "the continuous history of Northumbria, and indeed of England, begins with the reign of Æthelfrith", and that "he was the real founder of the historic Northumbrian kingdom, and he was remembered as the first great leader who had arisen among the northern Angles."
O historiador Frank Stenton dixo que "a historia continuada de Northumbria, e en efecto a de toda Inglaterra, comeza co reino de Æthelfrith", e que "el foi realmente o fundador do reino histórico de Northumbria, e foi lembrado como o primeiro gran líder que saíu dos anglos setentrionais".