Though remember the original Operation Princess service had a standard half hourly service as far south as Plymouth.
Not strictly true, normally 3 trains every two hours for Plymouth, the alternate 42 past the hour went to Cardiff according to my Operation Princess guide, but I submit to my mistake!
Unfortunately loading figures have led to some
HST▸ diagrams being stood down and the West Country has several route restrictions ruling out double Voyager set operation west of Plymouth. (No more than 7 car west of Plymouth, no more than 8 car south of Exeter).
Stock issues are always frustrating and there is generally no short term solution,
FGW▸ and my alma mater (operationally wise)
FSR▸ have in my opinion done well in using otherwise redundant loco hauled stock to be able to redeploy
DMUs▸ elsewhere.
My personal bright idea would be to trade
XC▸ 's HSTs for East Coast's Adelantes and then keep them pretty much on self-contained diagrams such as Manchester - Bristols (Alstom at Longsight would hopefully be able to maintain their own built trains) and Birmingham crews would be able to staff them if they went off route to Bournemouth or Newcastle.
I'll leave it at that for now, need to calm myself with some more wine and not think about my 4 car trip to Birmingham and back tomorrow!