Well done for the cunning extension to Smethwick
GB▸ . And there's quite a difference between ^80 and ^28.80.
This leads me onto another question. Why is there hardly any direct services between Cheltenham and Bromsgrove? I think it's something like just one service per day in each direction! Did there used to be more frequent services years ago?
Meanwhile, in response to XPT's second question, back in Central Trains days in Summer 1997, there were departures from Cheltenham to Bromsgrove at 07:15, 10:08, 12:01, 14:08, 18:20 and 20:19, returning at 07:54, 10:06, 12:03, 14:20, 16:19, 18:21 and 22:00.
The timetable pattern in those days was two two-hourly services between Cardiff and B'ham, one operated by Central (through to Nottingham) and one by Wales and West. Not especially-well integrated northbound, but southbound they gave nearly-hourly departures from B'ham.
But the logic about the intermediate stops was good. The Central ones came round through Worcester (and stopped at Bromsgrove), while Wales and West ran fast up the main line (and didn't). But the Wales and West ones did the intermediate stops between Newport and Gloucester while Central ran non-stop. That way you balance the running times.
As for XPT's first question, "why?", it's to do with handing the whole of the Cardiff - Nottingham to CrossCountry, and with giving
FGW▸ the Bristol - Worcester - Malvern corridor (which used to be very very poor indeed - just 1 southbound and 2 n'bound per day).
I still think that you could run an alternating two-hourly pattern on this corridor, which could coordinate with the two-hourly Bristol - Worcester. The Swiss, the Dutch, or the old Southern Region would do it that way. They'd want to rebuild Cheltenham station, but that's another story.