The Nexerus said
Or, you could look at it how Londoners do: the entirety of the UK that isn't London is basically a series of parasites feeding off the host body that is London.
Which is the opposite.
This shows were the vast majority of wealth is generated, note Aberdeen, the most northern city in scotland (unless you count inverness which is like, y'know, basically a town), it generates the second highest income. Also just note the north of england in general, some of those places are making at least a decent wage for themselves.
Now, let's look at where the money ends up.
London, and South East England (the place were successful people in london go to live and study, like Berkshire, Buckinhamshire, Hampshire, Sussex, Oxford, Surrey, Kent etc.)
They may be an economic powerhouse, but they're not helping out the rest of the UK by being one. It's a shown fact - they're taking more than they give.