(08 Aug 2022, 12:04 pm)R852 PRG wrote Prior to Crook closing and the X21 moving to Chester, Chester operated the X21 to Bishop Auckland on Sundays, interworking with the 21 at Durham. Through fares available. New drivers (and, by extension, former unit 2 drivers when the two main rotas were amalgamated in 2014) should have been route-learned to account for this but it is possible that some rarely worked any such duties prior to Crook's closure. Some former unit 1 drivers at Chester would have worked the route to Bishop during the Pink Angel days. 

Your anecdote reminded me of an occasion one Saturday not long after the 8/78 changed to Streetlites where an old hand on the 4-day rota asked me to go to Stanley and back with him on the 8 to keep him right. At the time, on a sixteen line rota, there was just a single duty where they covered the Stanley end of the 8 route, it being on a Saturday that they would each encounter once every sixteen weeks.

There weren't so many drivers that got confused with the core X21 route, I think some of the issues came about due to the extension of the X21 to Tindale Retail Park involving navigating a decker through Woodhouse estate, which didn't (and still doesn't) operate on a Sunday.
At that time, it still operated via Weardale drive, which meant it was an absolute maze to get through, especially since even the Solos/Versas that operated the old 18 service could barely get through with the badly parked cars, never mind a bloody StreetDeck!