[mytailorisrich]

And the FSA and Bank of England have a special unit to help, including a special "temporary permission regime" to ensure existing EEA banks will be able to continue operating in the UK while the new licences are sorted out for up to 3 years from the end of the transition period (end of this year), or even later as Treasury can extend it.

That is to say, they could have continued operating in the UK until at least 31st December 2023 with minimal overhead and no actual British bank licence.

This is why there is no panic or rush in the banking sector. Those who are announcing that they are leaving were already contemplating leaving for purely commercial reasons and are simply doing it now to simplify things (that way they don't need to look into the new regime or temporary regime at all).