So the net "winner" for financial services might be Germany? If I were looking for a new financial head office, I would be inclined to locate it in the EU's largest and most stable economy, right?
London is only the financial powerhouse it is because of its dubious status as the least regulated economy with access to the EU market. If they lose said access, that role naturally goes to Luxembourg, the next-least-regulated economy, and that's where these services will move to.
just as an aside, Luxembourg is not really an unregulated economy. it's very popular for fin companies because in addition to access to EU, the regulators (so I hear from my peers in legal) are very proactive speaking to companies to make it easier to set up there, and are quite prompt and more flexible than other countries in assisting companies on ambiguity in interpretation of regulations.
The city may lose up to 30% (google Euro clearing and ECB. I was always a big issue). It will move to Luxembourg, Frankfurt, Paris and Dublin. Possibly Scotland if Scotland decides to secede - a vague possibility.
