Why are fantasy world accents British?

[Morthoron]

Originally Posted by Lalwendë

historic setting?

...and about areas in Michigan which had lots of Cornish immigrants and retained some of the culture.

In Michigan, The Cornish stock mixed with immigrants from Norway in the state's Upper Peninsula (huge copper mining area), and became what is commonly known here as "Yoopers" (a bastardization of "Upper"). The nearest thing to "dah Yooper" accent is in dat dere movie Fargo, except even more pronounced, yah?