If i have the GWR route but not the east coastway route will the class 66 from GWR be able to be used instead for the southeastern HS route?
If you could, it would bring a whole suit of bugs. The GWE 66 doesn't know how to deal with TPWS grids the same way as the ECW one. So you end up with random brake applications if you accidently select the wrong one.