I think it is a B5LH that is being repainted, that green colour is the same as the "Green Arrows" wonder if the plan is for the 1A/1B to come under the same brand given they cross over each other at certain points between Newcastle & MetroCentre.
Alternatively I think it could be a first peak at the new livery similar to what the Yetongs will be branded in once they arrive as iirc that was going to be Green.
Could be entirely wrong however!
RE: Unknown B9 repaint