My understanding - although nothing has been finalised from our standpoint as we tend to only work up to 12 weeks ahead - is that the Maidenhead services will be peak hours only, akin to the current 387 operation (although from the proposed diagrams, the calling pattern will be very different). The aim is to get out of North Pole as soon as physically possible - once we have electrified stabling near London (West Ealing) that should be possible, as long as Reading TCD is ready to do the maintenance. Units will be swapped out by dragging them from West Ealing sidings to Reading on an as required basis. From what I gather it's complications with the latter of those requirements that is putting the process in doubt.