British police have issued advice on what to do if you’re caught up in a Paris-style terrorist situation.

Before going any further, I should stress that you are vanishingly unlikely ever to need their advice. I mentioned in this newspaper two weeks ago that we fear terrorism for the same reason that we play the lottery: Our brains are bad at computing probability. On the cold statistics, you’re more likely to drown in your bath than to die in a terrorist attack, more likely to be killed by a child than by a jihadi.