West Coast Main Line South: London Euston to Crewe. AWC - Class 390 & Class 221 LNR - Class 350 & Class 319 Drive High Speed from London Euston to Crewe with Avanti West Coast!! Or Drive Commuter with London Northwestern Railway, Also This Includes the Northampton Branch! This Route is 145 Miles (+10 For Northampton - Just a rough guess) Set in Modern time! (Mabye a pack based in the 80s)
You're unlikely to see a 145 mile UK route. Euston to Milton Keynes more realistic aspiration but it will just be another Lonfon commuter route albeit overhead AC rather than DC third rail.
Too long you might as well split this into different parts. These are WCML South Euston to New Street (shorter by 6 km 3.7 mi 180 km 112 mi than SFS Hannover Wurzburg Kassel-Wurzburg section 186 km 115 mi) WCML Trent Valley Line Stafford to Rugby (60 mi 96 km) where it can merge with WCML South. The last Section is WCML Stafford-Crewe. The route has 810 805 IET Avanti Paint Class 221 DEMU Class 92 Freight and Caledonian Sleeper services Freight Class 90 Class 325 Mail Train and Class 390 Pendolino. Retro trains Class 83 tap changer Class 86-87 Class 370 APT-E
correct and if you want to run that to Crewe which is 52 miles from Birmingham New Street. Then WCML Crewe-Birmingham New Street serves as the missing link I used the Railmiles engine to find the missing gap.