Molgrips, sorry but “Transport links to London are good BECAUSE London is so important, not the other way round. ” is bollox. Good transport links create demand, ask any road planner.
No, London grew partly because of the government choices of investment there. Canary Wharf because of incentives given in the 80s to build, while it was drawn away from manufacturing in the north. London is in the south-east, with most of the country to the north-west. The decisions to build national airports easily accessible only via London meant London prospered at the expense of elsewhere.
Decisions on transport matter. Birmingham grew partly because it was a canal hub, Thames Valley prospers because of Heathrow (that’s why all the US software companies are there), industrial estates grow out around motorways because of the accessibility of transport.
The north needs investment, and 4-tracking between Liverpool -MCR- Leeds- Hull will help a damn site more than HS2