Why not go the whole way and 'Balkanise' the UK . Economics have already done that .
As a good example on one of the day time property show a decent terraced 3 bed house in NI sold for 45k , following program had some hideous Russian woman in London arguing with her Polish builder over completion dates so she could install her 50k bed. That is an awful disparity in a very small country.
So allow Scotland NI amd Wales to go their own way. Yorkshire and NE is probably another area as in the NW. Pretty easy to cut up the rest and cut London adrift , it is after all full of 'foreigners' and criminals and we in the SE can charge them massive sums for food, water, sewage, use of airspace electricity etc etc etc.
Thats alla bit tongue in cheek but sadly the one size fits all model just doesnt work for us any more. Unlike much of Europe we dont have significant third and fourth parties who balance out different coalitions over time or in the US where the Feds only control so much of day to day life and even at the Federal level there are often balances between executive ad legislative.
Can any one here really claim that first past the post with its violent 'mood swings' has really served this country well since WW2?