Poops. Very good question which unfortunately has been hijacked above by nonsense and Ill-informed comment.
It’s both very complicated and simple at the same time. Official documentation runs to many hundreds of pages and our own internal one does too. The reason it is complicated is that different activities are covered by different passports which in turn have different treatments under equivalence (which is itself complicated). To keep things very simple, the most positive outcome is a deal that includes passporting. If that doesn’t happen we will move to equivalence (several different forms and process itself is complec but let’s keep it simple). This may require the relocation of some activities to Europe and again may require banks to have different legal structures (this is where it gets complicated). So skip the detail, Uk banks have subsidiaries in EU already – all in different centres despite the BS about Paris ^ – that already gives them passporting rights. So there is a lot of noise on the issue but as normal banks have already positioned themselves for all outcomes. Ultimately it’s a red herring. The CEO of Barc said as much last year.
All that remains is the ultimate detail which will determine which activities will need to be physically located. Bank estimates have gone from the 000s to the 00s ie approx 5% of people currently located in London max.
Bottom line – yes it’s a PITA but it is manageable and indeed has already been managed. In the meantime, the EU will creates lots of noise around “equivalence” as part of their negotiating tactic. This can be ignored unless you want to get lost in the kind of ill-Informed twiddle and mis-edukated comments that are being used to stifle understanding and overturn the democratic process.
If you want to get into the detail I would refer you to the EUs own study on the impact which is very thorough but stops before what banks are currently doing. It’s a long read though.