Potential problem with running a Crewe-Rugby service is the lack of north facing bay platforms at Rugby - IIRC they were removed when the station was modernized during the West Coast upgrade - meaning there's little scope for reversing southbound trains without creating conflicting moves.
Problem with extending a London-Northampton train to/from Crewe would likely be line capacity between Northampton and Rugby. Unless the New Street-Northampton frequency has been cut that section now has 3tph LNR, 4+tph AWC plus substantial freight flows as DIRFT is on this line
Problem with extending a London-Northampton train to/from Crewe would likely be line capacity between Northampton and Rugby. Unless the New Street-Northampton frequency has been cut that section now has 3tph LNR, 4+tph AWC plus substantial freight flows as DIRFT is on this line