In my time (late '70s and early '80s) there were up to 3 loco hauled stopping trains a day between Newcastle and Edinburgh (and v.v.) calling at pretty much every station including the likes of Manors, Pegswood and Chathill. Formations could be up to 9 or 10 Mark 1s though mostly 6 or 7. Motive power would be anything that Gateshead kicked out (31, 37, 40, 46, 47 or 55). See;
https://www.flickr.com/photos/127282573@N03/34778188536/in/photolist-UZeiNh
https://www.flickr.com/photos/127282573@N03/28094317159/in/photolist-JNAHGB-29TVkHD-2mGjGPc-2mGsjVZ
Hope this helps.
Douglas