I can remember those routes, but tended to remember the 777 as a Chester - Sunderland route, rather than going to Newcastle as it did towards the end. I think they re-routed it when the 26 was axed.
The 733 was a funny service. Did it go via Ouston, except on a Sunday when it went via Barley Mow?
There was even a short lived GNE route from Newcastle to somewhere like Spennymoor or Ferryhill along Durham Road in the mid-90's, that had a Gateshead two digit route number. I can't remember too much about that one though.
After I posted that last message, I counted up and reckon there were more buses per hour 15-20+ years ago along Durham Road than there are now... As well as the 26, Gateshead also operated the twice hourly 24, 25, 27 and 28 as far as Low Fell/Harlow Green. Chester tended to operate the hourly routes beyond there - all before Bus Lanes and priority lights were flavour of the month in Gateshead Civic Centre.
If I remember rightly, as well as the cross-Gateshead routes from West to East Gateshead, you had local services around some of the estates in Whickham, Blaydon, Beacon Lough etc running from Gateshead and the MetroCentre.
RE: Service Suggestions