People of modern British ancestry descend from many groups. Britain was under constant invasion from about 50 AD until 1066.
Here is an excellent book on that subject, Origins Of The British
I think that the problem was that the Vikings were scammed by travel agents.
No free boarding, no free ship parking, no welcoming wine and cheese party and no ATMs/Bank of Scandinavia Branches..
They had to get home after the fun and rowing a ship with a
RAM truck behind on a raft was difficult.
It'll be interesting when the history of colonization is done with improved knowledge of DNA included in the discussion.
Many Americans in the early 1800s believed the Mandan Indians were descended from Welsh explorers led by Prince Madoc around 1170 AD, as so many of them were so light skinned.