7. "RE: Gallian Gothic Book 3"
In response to message #0
>coals to Newcastle - A shortened form of "That's like taking >coals to Newcastle." Newcastle-upon-Tyne was a famous point of export >for English coal, so the idea of taking coals to Newcastle is a >shorthand for taking the trouble to do something unnecessary.
Notably, there was a businessman named Timothy Dexter who shipped coal to Newcastle after being convinced it was a common expression due to its good sense.