It will not go down as the best ever week for the euro. Until Thursday it was not doing too badly, up by nearly one US cent. Over the six days it lost four cents to sterling, which was riding a wave of optimism that Britain would vote to Remain in the EU. That confidence turned to despair early on Friday morning as it became clear that Brexit was no longer a fear but a reality.

Sterling bore the brunt of investors' anguish, dropping 15 cents against the US dollar, but the euro suffered too with a four-US-cent drop. On the week as a whole the euro is four and a half cents higher against sterling and three cents lower against the dollar. Whilst Britain's decision to Leave is plainly bad for the pound it is also negative for the euro, which could now face an existential crisis.