To rehabilitate the North, we need to split the pound in two. Let's have a London pound and an ex-London pound.
Currently it's like Greece-Germany in The Euro. Pound is priced for inelastic financial service exports in the city of London, which squeezes out regional manufacturers and leads to a culture of dependency on fiscal transfers.
If they had their own currency to competitively devalue, it could kick start the rebirth of manufacturing, increase regional tourism (staycations look cheaper from London now), generally get the rest of the UK going again.
London exports suffer a bit, but that's 'rebalancing'.