I'm going to take the opposing position. And for the record I was born in the north and lived/worked in the south for years.
London's probably one of the most successful and richest places on the planet, it's only rival on the global scale is New York. The only part of the UK that actually has a net contribution to the countries finances. Why take this money away and spend even more taxpayer money on useless vanity projects in the north that will have little benefit? London has been successful due to the entrepreneurial mindset and the willing to graft hard, not by sitting around blaming Thatcher for the last 40 years. Just like south Wales there is an atmosphere up here of blaming London and the SE for the regions own failings in adapting to the changing world. Manufacturing has gone. Heavy industry has gone. Mining has gone. Man up and start paying your own way instead of trying to live off of subsidies from the productive and profitable SE.
If that were true, then the Germans should only invest in Berlin, the French in Paris, the Dutch in Amsterdam, the Italians in Rome, and the Aussies in Sydney. All are major financial and commerce centers.
That this is not true in those countries suggests to me that it is probably not true in the UK either.