I feel it worth pointing out that the 180s were initially put into service to provide the new Paddington - Cardiff service (alongside the existing hourly Swansea HSTs), i.e. they weren't directly replacing HSTs, they were running an additional service, so the fact that they weren't as long as the HSTs was less of an issue (especially as many HSTs in the UK were a coach shorter before the shuffle around post-Princess etc)
They are looking fairly useless for the future (too short for most 125 mph services, too much space wasted with crumple zones etc for the kind of services that do need five coaches - most LDHS services are at least partly electrified so pure diesel is a waste), even before you take the reliability issues into account, but I cans see why they seemed a good idea twenty years ago (even if the story was that they were intended for routes like Rochdale - London?).
If they didn't have their initial reliability problems I would expect more would have been ordered so the issue of a micro fleet wouldn't be as much of a problem.
The prospectus that Arriva were handing out at Leeds station in around 2002 showed that they intended to run
four coach 180s if they'd won the TransPennine Express franchise - there's an alternative timeline in a parallel universe somewhere where Arriva won that bid and National Express ordered 180s to replace the 170s on the Midland Main Line, in which case we'd have had quite a big fleet of them spread across the network (based on the numbers of each class that were ordered).
Obviously it wasn't to be, but I can see that it might be preferable to have a fleet of around a hundred 180s (than a tiny class of 180s, a fairly small class of 222s and a medium sized class of 185s).
I thought about asking the same question. I think previous discussions found there were not going to be enough units for every service to run doubled, but it doesn’t actually follow from that that they need to split in service?
It's getting late but my memory is that you'd need
roughly eighteen units to provide a half hourly Sheffield - London - Nottingham - London - Sheffield service, and they've ordered thirty (?), so there's roughly enough units ordered to allow half of all diagrams to be doubled up (assuming say 10% spares/ maintenance etc), and the roughly nine hour duration of Sheffield - London - Nottingham - London - Sheffield would mean that the services arriving into London in the morning peak would be back in London to depart in the evening peak - obviously there's a large element of "back of fag packet" here but with just one type of train on all services through Wellingborough the dwell times at St Pancras should be a lot better than the current set up (and a fast northbound service can form a slow southbound service and vice versa), so it doesn't look as terrible as the numbers may suggest.
