Any speed in excess of the legal speed limit is inappropriate.
I can't agree with that one, joe-90.
Any speed in excess of the legal limit is
illegal.
Any speed in excess of a safe speed, given the conditions at the time, is inappropriate.
They aren't one and the same thing though. There are roads on which it would be entirely unsafe, at certain times of day, for me to drive a car at 60mph, although it would be ostensibly legal. At other times of day, I could do 120mph on my motorbike, on the very same roads, and although it would illegal, it would be safe.