If other parts of the country had the kind of investment in the infrastructure that helps to drive the local economy to the same extent as London gets funded then there would certainly not be the requirement for London to 'fund' the rest of the nation.
Compare the vast sums spent on Crossrail, Thameslink, tube maintenance, DLR expansion etc etc with the pennies spent across the rest of the country.
Invest in infrastructure outside of the SE of England and you'll find that the rest of the country doesn't require the money for benefits going forward.
In the SE tax payers money is spent on delivering infrastructure to make the region rich.
In the north tax payers money is spent on benefits payments that do nothing whatsoever to make the region richer and just lead to the area falling further behind the infrastructure rich region in the SE.