I wonder if GWR▸ might have been more agreeable if the Welsh Assembly pushed for and contributed to electrification of Filton Bank into Temple Meads?
I think you are a little optimistic about the prospect for traffic for Bristol beyond Gt Malvern **snip**
Ah, I was thinking Bristol - Hereford - Shrewsbury - Chester via the Maindee curve before Newport. Not a great distance. Suboptimal road connections. Hopefully the Maindee curve being singled hasn't screwed its capacity too much - before it was singled, didn't some Regional Railways services provide just that?
Mark