This was my only sighting of a Deltic on my relatively short visit to Darlington. All other workings observed had gone over to HSTs by this stage with Deltics largely confined south of York during daylight hours. Evidently, 55021 'Argyll & Sutherland Highlander' had worked north on the early hours but had been declared a failure at Newcastle with traction motor issues. It is being towed south (but strangely under power) to York as 0L01 with 40085 and is seen pulling away after being held at a red signal.
There is an audio recording of this event on my Youtube channel, see...
https://youtu.be/vRuHnSEGYrM