The History of British Accents

It's definitely something that's connected to like a fantasy genre or certain types of historical genres. To the average non upper class, non-traveling person through much of the history of the United States would have no idea what a real British accent would sound like. So something about the people first making movies and radio plays led them to start calling on British pronunciations to communicate a particular kind of message. But I don't know if that's the whole story.