The Midland Main Line (MML), sometimes also spelt Midland Mainline, is a major railway line from London to Sheffield in Yorkshire via the East Midlands. It comprises the lines from London's St Pancras station via Leicester, Derby/Nottingham and Chesterfield. Route map: Rolling stock: East Midlands Railway Class 810 Aurora bi-mode multiple unit East Midlands Railway Class 360 Desiro electric multiple unit Thameslink Class 700/1 Desiro City Electric Multiple Unit
What are you proposing here? In case you don't know, the section from Leicester to Derby & Nottingham already exists.
The whole section is way too long, and as pointed out, the middle section already exists in the game. (Unrelated side note, but I find it hilarious how that map doesn't point out the town of Worksop, but instead Kilton, one of its suburbs)
St Pancras to Bedford, Bedford to Leicester and then an extension on MML to Sheffield would probably be what would happen to make the whole of the midland mainline.
The problem here I can see, is unless DTG or another 3P can come to agreement with SHG, you are not going to see the most logical step which is the existing MML extended either north to Sheffield or south towards Bedford and London. Derby to Sheffield on its own not really long enough to be viable. And as it seems SHG have stepped back from TSW, at least the route building side, to do lawnmowers, not much chance of them doing it either.
