In 2006, David Cameron told Britain to be optimistic and to "let the sunshine in". Now the Tory leader says that UK society is broken and we should inject some morality into our public debate. Mr Cameron's sombre mood follows a recent spate of teenage murders in London. He is right that there is a problem, but his analysis is mistaken. Society at large is not broken, but there are specific problems that need addressing urgently.

Mr Cameron's diagnosis of a country in moral decline is normal for an opposition politician. Tony Blair, then shadow home secretary, voiced similar sentiments in 1993. But Mr Cameron's view should be taken seriously.