(19 Mar 2018, 2:20 pm)Jimmi wrote Services S1 & S2 are circular services now via Stannington. That's as much about the route as I can tell you due to a lack of information publicly available (couldn't bring myself to ask drivers). Seems to be the S1 one hour then the S2 the next hour, departing Morpeth Bus Station on the hour. Solo YM52TSU was on the S1 and the Centro was on the S2.
Some photos here (YM52TSU was operating on the S1 but drops onto the Morpeth Town Services for a few runs at around 10am).
PCL Travel: KX58BHN by Matthew Jimmison, on Flickr
PCL Travel: YM52TSU by Matthew Jimmison, on Flickr