in the North East the "Northern Powerhouse" seems a bit M62 corridor-centric
This impression is unfortunate but understandable. I suspect that the underlying problem is the early
PR emphasis on HS3 and sorting out the Liverpool-Leeds rail corridor in particular. But the real prize is to run frequent high-capacity high-speed trains all the way through from Liverpool to Newcastle. However, because that route from North Yorkshire northwards coincides with the ECML the final section doesn't require the same rebuild. York - Thirsk - Northallerton - Darlington - Durham - Chester-Le-Street - Newcastle can accommodate high-speed rail already. Though no doubt some upgrades will be tied in.
It is not in the interests of anybody to leave the NE out of the equation and I believe this is widely accepted.