In the absence of updates to the fleetlists on this site, I went searching the internet for possible alternative sources of information.
Having discounted the ukbuses one (too many obvious inaccuracies!), I stumbled across this one by "quack77": http://quack77.uk/fleetlists/fleet.php?ownerid=112
The page does note that the fleet list is incomplete; in particular there's an absence of Streetlites or Temsas. However, apart from these, my knowledge of the fleet suggests that it's otherwise quite accurate. Is anyone with better knowledge than mine able to verify that?
RE: Arriva North East: Latest News & Discussion - June 2019