It's too late to do anything about the Mk5s - the railway is stuck with these non-standard trains because First ordered them (and the small number of 397s) in a hurry instead of getting one fleet of Hitatchi trains to run all TPE services through Leeds and Preston (they aren't interested in the Cleethorpes line).
The fact that all three new fleets came into operation within a few weeks of each other means that the decision to order Mk5s looks poorer - it's not like they were ordering an "off the peg" train that would have been coming off the production line a couple of years before the "specialist" stock was built.
I was against the Mk5s at the time and I'm against them now - even if they had been built quickly and were reliable in service, it'd be a non-standard fleet.
But, we are stuck with them now. I can't see them getting scrapped any time (despite the way that enthusiasts like to talk about these things) - they may be better suited to a dedicated service though (e.g. a future Liverpool - Nottingham).
As for services in northern England... I keep saying this, but we have too many short trains cramming onto a limited amount of track - e.g. York was meant to have six or seven passenger trains on the line to Newcastle (depending on the First OAO) and seven passenger trains per hour on the line through Church Fenton to Leeds (i.e. ignoring the services via Harrogate). Both of which area recipe for unreliability on sections of two train railways with freight trains and flat junctions and no scope for overtaking at some intermediate stations (obviously the ECML has four tracks towards Northallerton, but there are also the Yarm services sharing those tracks).
The problem is the culture one everywhere having an hourly service to everywhere else. Fine for the people who do need a direct journey but how many people travel from Newcastle to Manchester Airport in a typical hour? A hundred? A dozen? Or are we basing the entire timetable (and the 15/45 minute splits in the two Newcastle - Manchester services) for the sake of a handful of passengers? Of course people prefer a through service, where possible, but people also kind of like a simple service, people also like a reliable service, and the messy combination of hourly routes makes that a lot harder to deliver on current infrastructure.
Fine if you want to build sufficient tracks/ platforms/ grade separation etc to make things work but we don't have that luxury at the moment - we have to work with what we have - cramming nine passenger trains per hour down the Burnage line to Manchester Airport (albeit providing a terrible service to suburban stations like Burnage, because most of these Airport services are non-stop beyond Piccadilly, for the sake of an average thirty-something departing passengers on every Airport service, seems to be asking for trouble. And one leaf on the line at Burnage will overspill into delays at Glasgow/ Edinburgh/ Newcastle/ Middlesbrough/ Cleethorpes/ Llandudno/ Liverpool/ Barrow etc.
Look at what works best elsewhere - look at how people who struggle to use "provincial" trains can work out how to use the London Underground after a few seconds of looking at a colourful diagram (the Underground isn't run on the basis of trying to provide an hourly Heathrow service to a dozen different termini - the Piccadilly line simply provides a frequent service on the route towards Cockfosters).
Stop running lots of short trains, focus on a simpler timetable that provides fewer/longer trains (which the infrastructure has a chance of coping with) - it's too late to do much about First's mistake in ordering three non-compatible fleets for their longer distance services but we can at least design a timetable around the infrastructure that we have, one that is simpler and therefore more reliable .
