Let’s be clear: restrictions on UK financial institutions’ ability to operate across the EU post Brexit if ‘passporting’ were curtailed is just one form of trade restriction like any other.  It is just that this is what it is called when applied to invisibles.  It is no different from the UK saying that, post Brexit, we will apply different type approval rules for cars made in continental Europe.  Illegal under WTO rules?   Maybe but we’ve got to be prepared to play hardball if we are going to get the best outcome for those in both the UK and elsewhere.   How long does it take to get the WTO to rule on a complaint? Quite some time I would surmise and BMW and Daimler Benz might not be so happy to have to stomach the costs to their businesses in the meantime.