Abredeen Airways, I think I remember HS748s operating for them (or was that Highland)?
Air Ecosse, part of Fairflight? (Again from a fading memory). Their Bandits were regular night time visitors at Luton on the Data Post runs, G-POST?
I visited Aberdeen during the late 1970's and Ecosse had quite a large fleet with their H.Q. over the far side of the airfield.