(23 Jul 2017, 2:34 pm)peter wrote I agree that 7509 is no more a spare vehicle than any other X21/2 branded example however I think the point trying to be made is that currently there is an extra X21/2 branded vehicle for the PVR as well as 7518 being the official spare. If by some miracle at any one time all vehicles were on the road - then there would be two vehicles left in the depot a X21/2 branded (7509 or any other) and the spare 7518.
It seems likely that with the less reliable 57-reg buses moving that rather than having 2 'spares' for the X21/2 and no spares for the 43/44/45 (12 new buses displace 12 buses to cover a PVR of 12) that an additional vehicle will transfer to Jesmond.
Surely 1512 would act as a spare in some form for the 43/44/45 although it pretty much seems to be permanently on the 685 due to the Omnicitys not being very reliable and probably because it's the closest vehicle to match the spec of the Cross Pennine Omni's.