BREXIT

1) Britain is more dependent on EU rather than other way round. The EU takes almost half of Britain's exports, whereas Britain takes less than 10% of EUs. And Britain's trade deficit is mostly with Germans and Spanish, not with the remaining 25 countries that would have to agree with the new deal.

2) The long term costs would go beyond economics. Brexit might well break up the UK itself. Scotland, more europhile than England, is again agitating for divorce. And the Irish government is among the most vocal foreign supporters of the campaign for Britain to stay in.

3) EU leaders know that brexit would weaken a club already mired in migrant and Euro crises. The EU has become increasingly important part of the west's foreign and security policy. Whether it comes to nuclear deal with Iran, threat of Islamic terrorism or sanctions against Russia.  

4) The 'Leave' campaign has proved aggressive and well financed. It has skirted past lack of clarity over alternatives to membership, instead playing up concerns over migration and loss of sovereignty to Brussels. Portraying those doubting if Britain could do better outside the EU as unpatriotic.