The breaking contract, regardless it being a 9xx work service, it's still a public service and anyone can board and alright where they see fit (For example get on in Jarrow and get off in Horsley Hill), and therefore the company should run the full route regardless if the vehicle is running empty or not, as not only they be fouling the contract, they also run afoul of the TC for failing to operate a service.
The 960 is indeed a contracted service, albeit a service contracted by Nexus and not the DWP. It isn't classed as a closed door service, in fact all Nexus contracts do allow normal people to use all services, school services were included (if you're brave enough) hence some say Scholars - All Passengers Welcome (as shown here on a 2024 shot -
https://www.flickr.com/photos/gjm-photog...3834438447), not sure if it's the case now, but all nexus contracted work services are still available to everyone.
Any closed door contracts I can think of is home to school contracts for Private Schools usually in the hands of coach companies, though one notable contract is the Jewish School in Gateshead which is operated by Go North East. As for work contracts, again Go North East has the Hospital Contract between the RVI and Freeman Hospital which is for NHS Staff Only, I believe it's also because it carries sensitive items / documents between the two locations too. I've seen Wardley Coaches going around picking people up for a work contract, not sure where they take them to, but have seen one of their coaches going through Wallsend and Walker picking and dropping people off.
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https://www.flickr.com/photos/gjm-photogenic/
Who needs heroes anyway? Villians have more fun.