Common pools are great as long as your service is one of the fat controllers favourites, and not bottom of priorities expendable when things get tight.
Also it won’t create loads of spare capacity for contingency - DfT/Treasury/consultants will say ‘this is more efficient so we can cut a load of resource out’ and everyone’s contingency will already be doing something elsewhere.
Is interoperability economic practicable with computerised trains? Just asking Alstom to bodge their shonky software even more, and add in more fault modes.
And if it isn’t possible to make backward compatible improvements then you have just fossilised your railway.
These are other rail issues, yes all part of the bigger picture, but just because one bit is broken isn't a reason to not try and move towards a less fragmented system. TPE with their recent problems are good example of what happens when you have a lot of different types of rolling stock, all of which requires specific training, it adds to costs and reduces efficency and ultimately the passengers suffer.
If a rolling stock supplier are unable to provide what is specified, or when they do it doesn't work then they are out of the reckoning for future contracts until they can demonstrate that they are in a position to deliver a reliable system.
Other industries manage interoperability of systems, in my industry we have certain standard protocols and I can buy hardware from a number of suppliers and be reasonably sure it will all work together, and some of this is safety critical. If it doesn't work, or takes a lot 'fixes' to get it to work then that supplier will not be considered for future projects. It does require standards to be set and enforced, and that requires a national passenger rail operator, even if there are brands within that operation. Drivers and other safety critical staff for passenger services should all work for the national operator.
In terms of rolling stock once you have a national standard for operation and control, with for example standardised HMI layouts and control then 'traction knowledge' comes down to understanding the dynamic characteristics, and particular issues surrounding the various flavours, diesel, electric, bi mode etc. Once a driver had been driving for a reasonable time the ideal situation would be that they would be able to drive any current passenger stock after a short familiarisation for each variant. The old SR idea that everything can MU with everything was the right idea, and should be the goal.
In terms of funding DfT/Treasury need to set service targets and allocate funding. Senior manager bonuses with the rail insustry are linked to those service targets,
The current DfT/Treasury/ToC triangle is not working, the 'GBR' operation needs to be arms length, and bearing in mind the investment cycles are long on the railways, continual tweaking and interfering needs stop, set a service level, and long term targets then only intervene if those in control fail.
Then start to address other issues, ticketing for example, which just seems to be get ever more complex.
And remember that large parts of the system are subsidised by taxpayers, I, in common with a lot of tax payers who are not at the extremes of the political spectrum have no issue with subsidies even for things that I dont use, I realise that it is part of sensible national strategy, but what I do take issue with is the large sums of money which just seem to be sucked in with no service improvement, or where in spite of subsidies the service is still dire due to bad decisions.
This is what I would like to happen:
All passenger operations except OAs to brought under the control of a national operator, a son of BR if you like. Currently we have a number of operations, Northern, LNER, TPE and SE, under direct control, as other franchises expire/fail bring them in. Within the national operation have 'brands' as others have suggested, Inter City, Regional Railways and various Metro services. Because all passenger drivers and guards (except OA) work for the national undertaking who also control the rolling stock in times of disruption there is more flexibility.
Freight remains as is, as I assume there are no direct subsidies, so it is competing with other modes
Network Rail should continue to deliver infrastructure, with a funded plan to bring skills in house, and reduce the dependence on sub contractors, which seem to be one of the issues that cause cost overruns. For example get a core team for electification in place and then deliver a steady flow of electrification, with a goal of eventually covering all inter city routes, then moving on to the busier regional routes.
Leave the current OA operators alone and still allow fresh applications. OAs are always going to be niche, but potentially fill gaps or develop markets.
Ticketing is national, no 'ToC' specific tickets, no ticket acceptance issues during disruption. If during normal service you want to allow people to use slower/specific services at a cheaper fare do that with advance tickets. OAs can offer advance tickets on their services at whatever rate they feel gives them a commercial return.
The problem with this approach is that to really show benefits its going to take more than one political cycle, probably 3 or 4, and that is always the stumbling block, coupled with politicians who want to be seen to be 'doing something'
Again - why this push for "standardisation" where it really isn't necessary ? Examples, the Pendolinos cannot work with other stock, however these are 9/11 car long distance express units, does it matter that they cannot be hooked up to a class 350 ? The infrastructure on the railways is such you couldn't run Pendolinos in multiple in any case, so they fact they aren't "common" really doesn't matter. Same with the 777s ordered for Merseyrail - it's an entirely self-contained metro network. Those units aren't going to suddenly be cascaded to Manchester or Newcastle, they won't even be cascaded to the south-east where 750v third rail is more common (apart from, perhaps, the Isle of Wight in around 2064), so again, why does the fact these aren't "standard" actually matter ?
Its not just about be able to work in multiple, its about driver knowledge, maintenance, and economy of scale. And as situations change todays Never becomes tomorrows 'If only'. A standardised consistent national fleet can only bring benefits, some of which may not be apparent until the need arises