That could well be the key to all of this. It's alright coming up with sensible plans, but if hourly HHD-CDF is what the WAG want then whenever happens will have to fit around that. At least it would give a half hourly service on the Marches which would be an improvement and could allow some existing services to be sped up.
If it also means the end of the current 2 hourly Holyheaf-Birmingham service it could also mean the end of 158s spending several hours on the North Wales Coast, meaning those ERTMS units could stay on the Cambrian where they are needed.
You don't need a frequent Holyhead-Cardiff service to gain those benifits though. The Holyhead-Birmingham can be cut back to just Chester-Birmingham and the current Holyhead-Cardiff could be turned into an hourly Chester-Cardiff service perhaps continuing to Liverpool over the Halton Curve every two hours. The only problem with that is that the northbound Chester-Cardiff would have to go via Crewe every two hours; otherwise it would be running in the Birmingham-Wrexham/Chester path. That could only be fixed if you could move the time of the northbound Swansea-Manchester services by half an hour, which would make for a long layover in MAN since the southbound timings aren't too far off.
To be fair if I'm reading it correct the Cambrian would be hourly all day, with every second running as a 4 car as far as Machynlleth, which would be a slight improvement. As you say though, it may need a bigger improvement than that to keep up with the growth down that line.
Yes, that is essentially the way I'm thinking, an hourly Aberystwyth-Birmingham service with every train being at least two units between Birmingham and Shrewsbury (between Birmingham and Machynlleth every 2hrs), and with Birmingham-Chester/Wrexham only every two hours (rather than hourly as, I think, Gareth Marston suggested) there might be more 158s available for attaching an extra unit on some services.
Also, as I said earlier in the topic, ideally W&B would have the 3-car 158s as well, so that some trains can be 5 or 6 car with two units (an Aberystwyth portion and a Pwllheli/Wrexham one). If only the 175s had UEGs, they could be an ideal fleet for the Cambrian with the 158s moving to provide 4-car trains into Manchester.
I would agree with this. Not because of the rolling stock, but that to me would seem to justify the mainly serving the Welsh market. ATW stopping Chester Warrington and Manchester would be logical with Northern serving the rest.
Trying to make English stations served by an English TOC was also a factor in my thinking, as it is with my comment that Crewe-Shrewbury intermediate stops should transfer to London Midland or Northern.
New diesel trains for regional routes have to be suitable to cascade to local routes unlikely to ever be electrified as per the long term rolling stock strategy.
The 195s wouldn't be much good for the Cambrian, HOWL or far north lines, those three (and many more besides) are at least Regional in my opinion (regional being one step above outer-suburban, which is the highest standard for which I consider the suburban door layout acceptable).
Helsby, Frodsham and Runcorn East.
There's nothing to say that they have to run the stopper.
My thinking is that those stops should be served by the Northern service, the W&B peak-extras and, in the case of Helsby and Frodsham, possibly also by the W&B Halton curve service.
Airport services are another bone of contention (not guaranteed after Ordsall Chord opens).
If the airport services aren't continued, then I hope the new operator will review its services and potentially use the other path (the one currently used for the peak extra) in one direction to cut down the turnaround time at MAN.