Re: Corbyn solution
>near instant gain of 25% in the capacity of the WCML, with an operating cost from lower ticket receipts of a few tens of million quid a year.
The trouble is that 'capacity' is only needed on a few trains, largely during peak period and then only those either running into London (morning) or out of London (evening) [Aside: I assume other parts of the coountry also have their own similar peak flows into and out-of the local business hub.]
In these specific instances I doubt the per train increase in seating will have that much effect (I'm thinking here of the services out of Euston on late afternoon/early evening Friday to destinations north of Birmingham, such as Manchester, Holyhead...)
This is yet another reason why HS2 is not going to solve the 'capacity' crisis. In fact is likely to get much much worse (*)
However, there is no reason why the operators can't experiment and operate a two tier first class service: basic - seats on peak commuter services but no frills, full service - normal or even enhanced service on non-peak services - thus encouraging greater business usage outside of peak hours of lightly used capacity.
(*) there are plans to build a new rail freight depot in Northamptonshire, ignoring the pro's and con's of the depot itself, the plans include giving access to the depot from the existing WCML tracks where currently trains can move at speeds of 100+ MPH, throw in a freight train either slowing to cross and enter the depot or accelerating to leave the depot - thus travelling at <30MPH, and you start to lose rather a lot of train slots aka capacity...