I was on one service from York 17/10/1976 (it was my 19th Birthday). My mate had moved to York and I went down to see him, went on a pub crawl round York then down to the station for the train (Deltic Hauled) which left at 23:55 and as I was reliably told, if your return train left before midnight you were OK for a day return. Crashed out on the train and woke later to see Electrifiction masts flashing by in the dark, we had been diverted via Carlisle so it was up to the window to listen to sweet sound of the Napier engines throbbing up Beattock, bonus was a trip round the Edinburgh Sub so that it was the right way round for the onward trip to Aberdeen.
This trip could be a contender for the "most diversions" as on top of the route already taken, the subsequent Edinburgh to Glasgow service (Push-Pull class 27s) was then diverted via Dalmeny (flooding at Winchburgh) then Falkirk Grahamston-Cumbernauld-Coatbridge-Rutherglen-Glasgow Central. The bummer was that I was heading home to Airdrie and a stop at Coatbridge Central would have been perfect, however we trundled straight through the station.
Jim