Another problem seems to be with the present timetable creating cross Birmingham New Street journeys here is that the frequencies either side of New Street does not really fit with anything, as it is every 20 minutes or thereabouts New Street - London Euston via Northampton, and for Rugeley Trent Valley via Walsall, and Liverpool Lime Street is every 30 minutes or thereabouts.
When I was at primary school many moons ago, 30 and 20 does not go.
Until when HS2 comes along, I believe a better outcome would be for the ex London Euston - Birmingham NS via Northampton to be as follows:
1tph terminates New Street
1tph runs to Crewe via Stoke-on-Trent
1tph runs to Liverpool Lime Street
The service pattern for the other routes would be:
1tph Birmingham International - Liverpool Lime Street
2tph London Euston - Crewe via ex Trent Valley Railway and the direct route between Stafford and Crewe
2tph Birmingham New Street - Rugeley TV via Walsall
2tph Tring local
2tph London Euston - Milton Keynes Central calling Harrow & Wealdstone, Watford Junction, Tring, Bletchley, and MK Central (if it can fit, with the calling pattern something like that or similar. Unsure how it would work though, or if it would upset a lot of passengers)
When HS2 eventually arrives (off topic for this thread though), I would recommend trimming the Birmingham via Northampton from every 20 minutes or thereabouts to every 30 minutes. I might have a go at designing a Taktplan (clock face departures) to see what a post-HS2 traditional Intercity, local, and regional express would look like along the ex London & Birmingham Railway section of the West Coast Mainline.