(24 Jan 2015, 11:35 am)Jimmi wrote Thing is express often doesn't tend to usually mean "fast" X more commonly means limited stop, example Arriva's X66 Darlington - Middlesbrough stops at certain stops in Darlington then non-stop to Stockton then non-stop to Middlesbrough.
Having limited-stop as 'X' is fine in my book. It takes the piss when you have routes like the X18/21/22 which stop at every place in the world.