For the head of an organisation devoted to the dissemination of ideas, Claire Fox displays a startling lack of original thinking.

To her credit, she does not argue that schools should be value-free zones. But the examples she uses to illustrate her case - multiculturalism, sustainable development and healthy eating - suggest less that she is uncomfortable with teachers exploring values with their pupils, more that she is concerned their teaching may not entirely conform to her own values.

Ms Fox is keen on Knowledge but how does she know that teachers spend their time “propagandising”? Isn’t that the point? Good teachers use evidence to develop pupils’ knowledge and understanding of the world, and on occasion use their professional judgement to explore different points of view. Polemicists such as Ms Fox express their opinion unburdened by the need to draw on evidence or experience: we might call it Knowledge of what they are talking about.

Dr John Hopkin, Birmingham.