@TheThinkingGoblin
Until you put more value on education and health up north (both metrics are awful), you won't be seeing much investment that produces jobs because the returns on said capital would be terrible vs other options.
You're ignoring all the high quality universities "up north" such as Leeds, Durham, York, Lancaster, Newcastle, etc., which attract good quality students from all over the UK, yes, including London and the SE. Trouble is they can't get jobs locally to their University, so there's a massive flow to London/SE when they graduate.
It's not all about the locals who were born and bred "up north". When there's an influx of high quality students from all over the UK, and abroad, it's a bit stupid that they can't stay in their northern cities after graduation because of lack of local jobs!
The lower educated and lower health "locals" are a different matter, but again, if there were thriving economies in their towns (fuelled by top quality graduates), they'd have more options for improving their lot!