As the debate rages around us, there should be at least one point of common agreement between “remainers” and “leavers”: the enormous significance of the decision. It is not an exaggeration to call it the most important decision for Britain since 1945. It has defining political, economic and social consequences.

On this, the international community are agreed. As they have looked on, first with a degree of bemusement and now, as we approach decision day, with alarm, they know that it will also affect the international economy and geopolitical relationships.

Talking to the financial community from America to China, I have found a near unanimous response — as with the Scottish referendum, they ask: “Why would you do that?” The difference with regard to Europe