Shall I save some time. The following will come up:
Carlisle > Nottingham
St Pancras > Glasgow via the S&C and perhaps Kilmarnock
Brighton back on XC
Insert random northern town name to Kings Cross via other random northern town names.
Can I ask why? I love Whitby but running a direct train from London is utterly pointless and a massive waste of resource. What would be of more use are a few more local services on the Esk Valley branch and some track work to support them.
Also why on earth would you use that route from London to Blackpool when you could walk to Euston and be in Blackpool in a fraction of the time.
Not sure about half hourly but that is about the most sensible suggestion on here! Can we also run a similar service along the Marston Vale