In a historical linguistics class, we're currently working on the decline of the thou/thee forms in English. The evidence is very sketchy for America, but I've been told -- not sure how much to trust the authority -- that thee/thou are still used among intimates around Sheffield; my informant says Sheffielders are sometimes called "dee-dahs" on this account. The info is at least twenty years old, and I have only the one source. Is it accurate today, or was it ever? Is the distinction still in operation? Any data is appreciated -- best if you can give me a city and a year.

Adam