I spent a few days in Plymouth, Mass. recently while profiling a historic interpreter at Plimoth Plantation, a recreation of the original Pilgrim settlement. The interpreters speak in what they call dialect, a recreation of the English accents (and Dutch, as required) that would have been heard in the early colonies. The level of specificity is incredible: interpreter training manuals include lines such as, "Appendix C - Polysyllabic Words with Probably Accents in 17th C." and separate sections for vowel and consonant variations for different English cities. (Malka Benjamin, the woman I profiled, played a character from London).
I really can't imagine spending the entire day speaking in a 17th century British accent. Malka told me that she used to have trouble turning it off at the end of the day, realizing she was still speaking with an accent at the grocery store after work. Today, she has that under control, "But I say vex a lot," she admits.
You can read my profile here, and listen to Malka learning a traditional song (with a few snippets of Pilgrim speech) below.