(05 Oct 2021, 2:02 pm)Dan wrote No. Arriva can't bid for Metro Replacement, the only operators that can are Go North East, Stagecoach and JH Coaches.

Stagecoach have never bid for a Metro Replacement contract yet (presumably isn't worth the hassle to them), so it's only really out of Go North East and JH Coaches. As I said before, I'd imagine Nexus will specify that the Miscellaneous Works contracts from September 2022 must be Euro 6. All the buses operating these services currently (Volvo B7TL, Scania OmniDekka, Dennis Trident) can be upgraded to Euro 6.