Ah. I think I was referring to secondary routes rather than Branch line stock. Should have clarified.
However a further idea which has just come up in my brain. This may not be a well received suggestion for Long Distance Passengers and is only theoretical. But why not extend some if the Paddington bound services onto the branches aka Newquay during the summer. You could run an hourly
HST▸ to Avonmouth and back to Paddington. Thus freeing up a 150 (Example). For the same route you could run a
PAD» - Cardiff/Swansea service via that line calling at SVB Line stations as an alternate route?
Could the same be done for Gunnislake and Okehampton branches?
I've also thought about running a HST (Possibly 5 car set) from Paddington to Weymouth non stop to Bristol Parkway and Bristol Temple Meads. Then take the path of say the 17:49 which can be a very cosy service down the Trowbridge line! Of course that would assume a set which didn't have any
LSL‡ (Long Swing Link) Bogies in the consist...
increases capacity on an already busy service with a comfortable train. Whilst elliviating overcrowding for passengers travelling just to Bristol by having a dedicated Fast service. But also for Bath Spa & Chippenham passengers who have more seats on existing Bristol Trains. And the best bit. You've done 2 diagrams with 1 set
I think these are rather far-fetched, if I've interpreted you correctly.
Extending London - Bristol services to Avonmouth. Needs an extra 2 HST diagrams - services much slower on the Avonmouth line due to selective door opening, only 2 doors per coach meaning longer dwell times, and the need to ensure all the doors are shut at each station.
Routing London to Swansea services via Avonmouth (I think that's what you were suggesting?) Similar problems to above and would add about 90 minutes to South Wales journey times.
London to Weymouth via Bristol. Again, same problems with dwell times and needs an extra HST in the peak usage period.
Why would you use an HST on local lines for which they are wholly inappropriate? The only reason Newquay gets one is because of the particular need for a through service from London, the volume, and the fact that luggage is a key factor on that route.