This is not completely done yet, I just decided to publish it because I have put it off for too long. This is not an official map, this is just my take on it. I tried to loosely follow the original NCR map, but I added a lot and took out some things. Several location names were completely changed or slightly modified to fit in with Scottish, Latin, and Welsh language roots. Key: Yellow is the Mainline Secondary. Blue is the Main Line. Dark green is the Bargmouth Branch. Red is the Lilacbury Branch. Dark Blue is the Brynmauyer Branch. Grey is a goods line. Orange is the London, Midland, and Scottish Railway. Also, the plane markers are airfields, not airports. I also imagined this being located between Wales and Scotland along the coast.
Credit to Cobra0101.