Where radical Islamism is going to be a factor, it's going to be very, very tough.

The art of leadership is saying no, not saying yes. It is very easy to say yes.

The problem is some of the populism on both the far left and the far right, it can make a Tweet but not make a policy. And, you know, when you are dealing with issues that are as important and serious as this, I understand why people search for simple solutions.

But I am an optimist about Britain; and the difference between an optimist and a pessimist is not that the optimist believes the world is wonderful and the pessimist believes it's beset by challenges; the difference is the pessimist believes we will be defeated by them; the optimist thinks the challenges can be overcome.

I think we've, again, got to be extremely careful; otherwise we'll misunderstand what's going on in Iraq and in Syria today. Of course, you can't say that those of us who removed Saddam in 2003 bear no responsibility for the situation in 2015.

So much of politics is about the daily grind of political business: the people to see, the myriad different facets of government, the remorseless agenda of this part of the media or that.

But the world is ever more interdependent. Stock markets and economies rise and fall together. Confidence is the key to prosperity. Insecurity spreads like contagion. So people crave stability and order.