It’s a tiny ass island yet whenever a British person hears another British person they’ll be like “Oi guvenor! I know exactly where in Merry-ol-England they are from! Clearly they’re from Bovinshire-upon-Weavilton!” And Bovinshire-upon-Weavilton is a town like 10 minutes away from where they live.
Americans speak a little like 17th-18th century Brits but honestly Devon or Cornwall is closest. Just talk literally like a pirate and you’re mostly there. The John Adams tv series is painfully lib but gets that right.
Also if you go back to Henry Viii things start going Dutch/Frisian. which is concerning