Stupid! Donald Trump is an AMERICAN, not a Brit. He connects with Americans because he sounds like an American and expresses himself in language the average American can understand. A Brit accent would not fit his image, AND would be far too insulting for many who are sick and tired of the British incursion into our news scene......like me!
The British accent may be considered by some to be “sophisticated,” but I consider sophistication to be the condition of a person’s knowledge....and a lot of that knowledge comes from interacting in the real world, not simply being derived from books.
Besides, many British English words have different meanings in American English. Why does the Oxford Dictionary differ from the Webster Dictionary ? Why should an American adapt a British accent? It would be a VERY STUPID move.
It might be considered the trans-Atlantic accent that was popularized in American stage and film during the 40’s.