Flood the market in underdeveloped areas - that will attract workers and lower wages to attract employers.
Or the councils in the South East would see the cheaper housing and use it as a way to dispense with their housing waiting lists and troublesome families in social housing - which is hardly a recipe for economic dynamism in the North
I think the standard of living would have to get very low indeed for employers to forgo the economic agglomeration advantages of major urban blocks.
Also "underdeveloped areas" tend to involve AONBs and National Parks in my experience.
Can’t keep hothousing the southeast - it’s overcrowded, and the north needs the investment.
The problem is that the economic realities of the time favour ever larger economic agglomerations.
People living in larger city areas tend to be richer on average because the local economy is better able to leverage specialised chains of production and services.
Whilst it is likely
possible to brute force this through financial transfers to rural areas, it would be enormously expensive and I have little faith that the resources are actually available given all the other stresses on the British state.
Many of the small settlements in England and elsewhere have little reason to exist in an economy without massive manufacturing and with little agricultural employment.
Pit villages with no pits are not going to function as real sources of wealth and improving living standards, no matter how much money is thrown at them.
Neither are agricultural market towns with no agricultural markets.
If not for planning law, many of these places would have gone the way of Old Sarum already - but they can't because urban development is functionally frozen in 1947.
The central question is, do we want to level up towns, or the people in them?
By far the easiest way to do the latter is to ensure that people who wish to move to London or other wealthier areas, can do so.