there are two 'london's' in the same general area in england. one isn't anything you'd imagine and that one is explored to some degree here;

The City of London is effectively an independent city-state * existing inside greater London.[1]
[2]
[3]
 However, its nature is unique and complicated. It is not so neat and tidy as is the Vatican for example, which is clearly a separate sovereign entity nestled within the city of Rome. Still, the City of London has its own government and police force, makes its own laws and levies its own taxes. It has its own flag, crest, and ceremonial armed forces. I have seen one reference stating that the City also has its own port. I could not find an independent confirmation of this, but it would fit the pattern and the City does have some responsibilities for London ports, so this is plausible. If true, it would be stunning because that would mean that the City could bring in products of any kind including currency, precious metals, cocaine, and also people, without the permission or even knowledge of UK customs and immigration or the UK government.

* In performing a search the other day, I was first met with a notice in capital letters telling me “The City of London is not a sovereign state”, followed by a small avalanche of websites all doing “fact-checking” and “misinformation-debunking” to assure me the City of London was NOT an independent anything. There is hardly a sign more certain that we are onto something important, than when 25 Jewish websites leap up to tell us “There’s nothing to see here”........more........