Where did it come from?

I had previously decided that the southern American accent is closer to the English list heard in England itself and likely finds origins there, something to do with aristocracy.  Because of the need of slaves.  But, as I hear Scandinavians speak English, they have a more American sounding accent. And without conciously considering it, I thought well, that makes sense because Old English and Old Norse practically sound the same. I often not how similar Swedish words are, my kids can tell what I am saying in Icelandic and Dutch quite easily without ever studying vocabulary. Ok, ok, that seems sensible, but where the heck did the Formal English pronunciations come from. I haven't ever said, but Scottish/Irish share alot with Icelandic and that can be explained by Celtic migrations and colonization, but it is something Aural about how they speak the words in England that us unique and I honestly do not know where that dialect comes from.