(28 May 2020, 4:04 pm)Storx wrote It's so they can reduce the frequency of the 1 from Gateshead to Whitley to every 20 minutes. It wouldn't work having the the Wrekenton and Metro Centre parts as you need 4 buses an hour. It obviously doesn't have enough passengers to carry on it's own so they've merged it with the 25 the least of the important buses going towards Wrekenton / Low Fell.  All about cost savings and reducing the PVR in my opinion. 

I agree that this will be a factor - the fleet size is getting smaller and smaller.
However if Durham Road wasn't a factor, they could have diverted the Q1/Q2 off Easedale Gardens as an example and removed the Harlow Green - Durham Road link. 

Whilst there are some positives around the 21 serving the Arnison Centre, I can see it resulting in reliability issues - with a subsequent knock on effect along the Durham Road. What better than to offer an alternative in the form of the 25? Slightly longer journey, but still serves key parts of the 21 route.