(11 Aug 2013, 3:49 pm)gtomlinson wrote Only reason I can think of (and its stretching it) is that Church Road/Valley Drive is an affluent area with high car ownership and ridership beyond Gateshead was fairly low
There was certainly enough passengers that used to travel beyond Gateshead and into Newcastle on the 51 to justify it running to there.
The reason (or excuse) that was given at the time I think, although I'm not 100% sure, was that it ceased to serve Newcastle to improve the reliability of the service.
The reliability of the service got worse when it became a circular route, so it was less problematic as the 27 from Newcastle-Heworth. In which case, to improve reliability the best answer wouldn't be to terminate the Orbit at Gateshead, but to split to route in two at Heworth, going back to the old 27.