Dear Friend,

In the UK we have a famously colourful popular press. It’s often chided for its inaccuracy, triviality and childish obsession with celebrity, but just occasionally it is capable of expressing in simple words what much of the population is feeling.

Today is one of those days — “Get back in your cave” the headline of the Sun newspaper tells Ayman al-Zawahri, supposed right hand man of Osama Bin Laden, after a tape showing the terrorist gloating over the recent bombs in London popped up on the Al-Jazeera Arabic TV network.

At times like these a little British pluck and good humour can go a long way to raising spirits. But as we know, the problem is not Mr al-Zawahri in his cave, wherever it may turn out to be — it is young disillusioned British citizens who have decided to strike at their neighbours.

The global terrorism problem is much more complex than a simple black and white analysis will allow and the chances of it “getting back into its cave” any time soon is pretty remote.

So in this environment it is all the more remarkable that almost four years on from 9/11 a US Treasury survey of US insurance buyers has found that roughly four in ten of buyers with exposures in big cities still buy no terrorism cover whatsoever. Where's the sense in that?