system
Given the following post, respond as if you're commenting on Reddit:
human
Why is the UK so economically dominated by London?

I get the impression that the UK's economic activity is particularly skewed towards London, with the rest of the UK lagging behind a lot. Other countries often have strong centres of economic activity outside their capital city. 

This seems to cause a lot of problems (high house prices and overcrowding in London, a feeling of left-behindness elsewhere) so I would be interested in knowing why it's happening.
gpt
History. Historically the UK government centered in London, and when the country grew in size and power (to a great extent due to the government) that growth lead to growth in the Capitol. This happened early on (late medieval/early modern period). Countries that centralized government relatively late tend to have more large cities outside the capitol (Germany, the Netherlands and US have had decentralized states and have many large cities. Countries like France, Turkey (counting Istanbul, not Ankara) and England have a bigger gap between the largest city and the rest). 
That being said, many other countries also experience similar issues in their mayor cities.