David Cameron ducks a debate with Alex Salmond. This makes sense but is still depressing.

A novice poker player quickly learns – or had better quickly learn – that strength often connotes weakness and weakness is a reliable indicator of strength. But as the stakes increase and the level of play becomes more sophisticated such elementary tells can be misleading. They are false friends in the land of the double and triple bluff.

So a novice poker player might conclude that David Cameron’s refusal to debate against Alex Salmond is a sign of weakness. A slightly more experienced player would think this weakness too obvious to be true and conclude that Cameron is holding better cards than he is indicating. And it is true: with the polls indicating a No vote Cameron has little need to risk a debate the outcome of which must be uncertain. He is, if you like, the chip leader and need only play occasionally and when he thinks he’s on a sure thing.