Ask any trading practitioner what their biggest potential headache of 2016 is and most would have said – without hesitation – Mifid II. That is, until a few weeks ago.

With a year-long delay to the European Union's revised trading rulebook now looking likely, and many implementation projects on ice, thoughts are turning to another issue looming over Europe: Brexit. A referendum on whether the UK should remain in the EU is set take place before the end of 2017 but many think the sooner it takes place, the better.