 In 2003 a paper was published by Christian Capelli and colleagues which supported, but modified, the conclusions of Weale and colleagues.This paper, which sampled Great Britain and Ireland on a grid, found a smaller difference between Welsh and English samples, with a gradual decrease in Haplogroup I frequency moving westwards in southern Great Britain.The results suggested to the authors that Norwegian Vikings invaders had heavily influenced the northern area of the British Isles, but that both English and mainland Scottish samples all have German/Danish influence.