(08 Nov 2015, 7:31 pm)GX03 SVC wrote Could possibly be route learning. Very strange that there are 3 vehicles NIS up there overwise.
Could possibly run off an X16 but overwise it's a rare working.
Could possibly be swapping buses between Ashington & Alnwick? Redcar do this quite a lot with Whitby to balance the fleet depending on requirements. This is on top of swapping buses on service runs.