The TfW 150s are not in the same category. Severe corrosion and mechanical issues and reliability below the trains that are replacing them. There shouldn't still be any 150s still in service anywhere in the country. A case of needs must.
Despite that, they've been almost the only fleet keeping the Marches line operational at times over the past year, although less so now I think. They've also had to cope with trying to keep to a timetable designed for much faster trains.
As a passenger they're far from my favourite trains (even less favourite if I'd encountered one on a route as long as that), but I am impressed by the way they've managed to keep on working, old tech and all. There again, maybe its because they're old and therefore simple tech that they can be kept going so long.
Back towards the topic, I suspect our informative correspondent Warren T Manager has a hand in keeping the 455s alive for as long as they may be needed. Though I doubt even he knows how long it'll be before the 458/4s begin to help out, let alone the 701s.