I've seen stories about this a few times before. Supposedly the town was "rewired and grounded", at which point the problem stopped for a while. Apparently it has started again and now the problem persists even though all the electric power in the town supposedly remains turned off.
Maybe there's a (misconnected) generator somewhere that no one knows about. Or maybe it is time to sacrifice a goat!
If the earth return from the railway has a high resistance through some geological phenomenon, is it possible that a heavily loaded loco could cause the village earth potential to rise by several kV relative to the LV distribution system?