There would be a significant loss of competition, just because Stagecoach run in Newcastle doesn't make it automatically okay.

The CMA would look at the current market and compare it against what it would look like. Arriva compete with GNE all across North Tyneside and South Northumberland, plus County Durham and East Durham.

Stagecoach compete in Teesside, Hartlepool and Central Newcastle, that's about it.

In the very unlikely event it was sold by operating company, if GNE bought Arriva Northumbria, on the basis of what I outlined above, the CMA would deem it a significant reduction in competition and as such, could enforce certain things (reductions etc). Stagecoach would be preferred from the CMA point of view as it would maintain competition on most (if not all routes).

The opposite would be true in Darlington/Teesside, as GNE would be preferred, as it would still be two core operators.