In my opinion services around Seaham declined when they started withdrawing the local service and absorbing them into the longer distance routes, which then agains stilts growth on those services as they’re restricted to mini buses (MPD, Solo) which of course can quickly overcrowd and routes take longer to get to the end destination. Even the mid-to late 2000s you had the Seaham circular doing the local stuff around Deneside, Westlea and Northlea, which meant that the routes going out of town could take more direct routes. Arriva did the same in Peterlee with service 24 now taking a year and a day to get round Peterlee, GNE currently doing it with the Peterlee extension of the 61 around Murton too.

If you had a Houghton to Seaham bus that went direct from the Harbour via Station Road and Seaton, maybe as an X1 extension it could be relatively quick and then offer new connections to Seaham, Washington, Newcastle. For years, GNE had an every ten minutes X1 and a half hourly 55 (X5/X35 etc,) going between Houghton and Easington Lane + the 35 half hourly too, which was overkill on that corridor. Rerouting one or two an hour could have opened up more people on that section of route who were going further afield, and you were still giving a very decent service on the corridor to Easington lane. They tried doing a bit of that at one stage as the X4 but if I remember it was pretty much 90 minutes end to end and seemed to serve any possible location along the way.