My suggestions about the M1 workings were correct, the 10:00 from Morpeth and return interworks with the S1 and the afternoon run this afternoon was Dart LG02FFP.
I decided to sample PCL Travel's efforts on the 15/16 and M1 this afternoon, here's what happened.
I got the 14:15 service 15 from Alnwick with Dart LG02FFR being allocated for this journey, I decided to sit at the back for this journey, avoiding the Urban90's seats of course! first thing I noticed was one of the panels behind the seat was just layed along the ledge over the engine with a canister or something plus wiring being exposed as a result (see photo below). Dart as expected wasn't the greatest bus in the world especially being ex London, it was alright on the straights but the performance on hills wasn't great.
I stayed on-board to ride the circular service 16 with the nice views, just a shame that there is no guided tours anymore.
Upon return to Thropton I had intended to catch their commercial service M1 to Morpeth with Dart LG02FFP being allocated for this run, unfortunately after a driver changeover with the drivers between both services, LG02FFP wouldn't start, both drivers attempting to start the failed Dart but no joy, I was hoping that they would give up after about 10-15 minutes and just send the 16/15 which was working on it's way, but no, both drivers kept on attempting to start the stricken Dart, they left both buses and went to a nearby petrol station to get something to possibly help start the bus, but it was hopeless, so sometime after 16:30 they finally gave up and finally me and the Dart on the 16/15 were on the way to Alnwick, 45 minutes late with me spending that whole time loitering in Thropton wondering how I was going to get home and I had no mobile signal in Thropton so I couldn't alert anyone to the situation I was in (annoyingly just before leaving I discovered that I could have used the Three Wheat Heads' WiFi).
I am now currently on the X15 to Newcastle when I should be somewhere near Chester-le-Street and won't be getting home until around 9pm now. Needless to say, am not amused by this and I have zero desires to ever use one of their services again.