Even more stupid is that all the journeys are diesel under the wires.
It's more likely to work than running an electric train away from the wires / third rail
In all seriousness, as the balance of requirements changes I wouldn't see any reason that diesels shouldn't run on electric lines from time to time. But where it's done regularly, and when there's a serious shortage of carriages and services on certain diesel lines (such as our local one), it's rubbing salt into the wounds to scrap perfectly working old electric trains and then use diesels.
