We all know Brexit has upturned British politics, but nobody knows how Brexit will look in the weeks or years ahead. As British politicians admit, we are in uncharted waters. So why did Brexit occur and is it reversible? Or was it inevitable, given Britain’s history? Brexit is also the most serious confrontation for the EU for many decades, while the EU also has to deal with the major challenges of migration, populism, economic coherence, and new threats in an era of global technological change. What strategies should the EU deploy now? What role should individual EU member states play? Can Brexit help us understand how EU politics and the international system is changing?