What time does the 865 travel to/from Seaham?
Obviously where I saw the decker, it wasnt on the 265/865 route - but it may explain the bus being where it was.
The only other suggestion I could think of, was that a bus already in the area was working a short, due to an earlier breakdown etc and another vehicle picking up the rest of the route from Seaham.
Edit: Forgot to mention the 877. I often used to see a bus on a morning running light from Chester, which I always assumed picked up a short working somewhere to Seaham and then starting off on the 65s (I always saw the same bus later in the day working the 65). It may be the short working was that 877. What sort of route does it take and what sort of timings does it have?
RE: Go North East