The once-a-day 304 to Preston always looked out of place going through Wigan too. I think I read somewhere that this EMU was provided as something of a staff train when some BR jobs based at Crewe were relocated to Preston - maybe to placate union objections.
In the 1975 timetable this ran as 1P82 09:17 from Crewe, calling at Hartford, Warrington & Wigan, arriving Preston at 10:10
Return was 1K82 15:00 from Preston, stopping Wigan and Warrington only, arriving Crewe at 15:54.
I wonder if the Crewe crew were booked to spend the day playing cards and drinking tea in the Preston mess room in true 1970s style? Maybe one of those turns for the old hands just about to retire?
I doubt it was any sort of staff train. Even in the 70s a working day from 1015 to 1450 would have been too generous!
There was a staff train the other way round - Preston to Crewe in the morning and back around 1700. Normally a 2car Cravens unit - a type otherwise pretty rare in Crewe. Always seemed to be worked by a grizzled Prestonian driver still in his L&Y uniform.
And, yes, I think it's quite possible that it was a cushy Crewe turn on 1P82/1K82. Less than two hours of driving; PNB of nearly five hours! (Though it might have balanced with a Preston - Crewe PNB Crewe - Preston slice of work.)