Isn't the whole point of the City of London, to be a legal money laundering economic zone, that brings banks, corporations, money and jobs to the UK?

Specifically the Eurodollar is the main reason for the City of London to exist.

Eurodollars are US dollar deposits at European banks. Originally these were used as a way to give the Soviet Union access to the dollar markets through French banks, but eventually it became a way for basically anyone to participate in dollar exchange who can't have a US bank account.

https://en.wikipedia.org/wiki/Eurodollar

Pretty much, yes.