OK, I've brought Table 65 up again to clarify things. The XX:00 is first stop Stoke-on-Trent, XX:07 is first stop Stafford, XX:30 is first stop Warrington, and XX:40 is first stop Crewe. All four can run via HS2, because they do not serve anywhere south of Tamworth. This will be temporary, but I assume the junction will remain in place, so there will still be the option to route them that way later on. The XX:10 and XX:20 can carry on as normal, as can the current Birmingham services, although I would like to see them increasing the number of calls at Rugby. That gives you four 125mph paths without any reduction in service to any station.
Table 66 services will be able to readjust to exploit these extra paths, plus the spare Pendys freed up by HS2-CC stock taking over many WCML expresses. This will provide an increase in speed, hopefully extra calls at Rugby for expresses and at least two extra freight paths. I'd like to see a Glasgow semi-fast or a Blackpool service as well, but that's probably impossible.
From what I can remember, the remaining Intercity services on the WCML following the opening of HS2 are intended to be:
2tph Birmingham
2tph Manchester
1tph Liverpool
I think there's also mention of 1tph to Glasgow remaining, however I think this would be better terminated at Preston (or maybe Lancaster) to connect into the Glasgow service running off HS2, as there would be precious little space on the WCML North of Preston with two London to Glasgow trains per hour (One WCML and one HS2) and possibly three in the peak.
I'd expect these trains to have additional stops added, and for journey times to be extended somewhere in the region of 15-20 minutes to accomodate the additional station stops, reduce pathing conflicts and encourage passengers making the end to end journeys (Or almost end to end journeys) to make use of HS2. So the stopping pattern for the WCML IC services could look something like this:
Birminghams: Bham Intl, Coventry, Milton Keynes, Euston
Manchesters: Stockport, Macclesfield (Peaks only), Stoke, Stafford, Rugby, Watford Junction, Euston
Liverpools: Liverpool South Parkway, Crewe, Nuneaton, Milton Keynes, Euston
Glasgows/Prestons: Preston, Wigan, Warrington, Crewe, Rugby, Watford Junction, Euston.
There's plenty of scope for more stops to be made out of any of those services as well. What I'm getting at is that while journey times from Milton Keynes to London may be increased by five minutes and Rugby to London by ten minutes against the current times, this will be compensated by having double the frequency of Intercity trains than at present calling there, reducing waiting times and increasing the convenience of the service.
If you want to travel from say Stoke or Coventry to Milton Keynes, the service will be improved through having an increased frequency of trains, whereas any passengers from Stoke or Coventry travelling to London would be encouraged to travel via HS2 (changing at Birmingham) through the slowing of journey times on the WCML.
There is proposed to be twice the number of Regional semi-fasts in operation: 2tph via the Trent Valley and 2tph running to/through Birmingham. It is these services which I suspect would be operated by displaced Pendolinos (Previous calculations on this forum have estimated that around twenty Pendolinos may be freed up), so could utilise the fast lines at 125mph. Given that there aren't that many doubled up 350 formations on the semi-fasts, this roughly quadruples the capacity of the semi-fasts, using trains twice as long running at twice the frequency. This just leaves the stoppers on the slow lines, which with a regular stopping pattern means that their average speed isn't much greater than that of a 75mph Freightliner.
Sounds like a pretty major range of capacity increases to me.