The original idea, that of preventing war, appears to have worked because no European nation has gone to war with another in the 75 years since the closing of the Second World War. The ancient enmity of France versus Germany has ended. England is not required to see itself as a balancing force on the continent. And in that sense, the EU is a good thing.
But what has also worked is the linking up of the economies. Nations that needed human capital and labour benefited from the movement of such assets through their borders.
About 20 years ago, after Poland was brought into the EU, the UK opened up its borders to Polish migrants. There are an estimated 30 lakh migrants in the UK today and there are 10 lakh Britons living in Europe, mostly in Spain. And the EU continues to expand towards the east. It has a customs union with Turkey which has long sought EU membership with the claim that part of its country, the side in which Istanbul is, lies in Europe. There are also expanding ties with former Soviet states.