Hans van Broekman, principal of Liverpool College, writes:

Richard Walden, head of the Independent Schools Association (an organisation many will not have heard of), has declared that state schools are churning out amoral children because of a focus on league tables. In contrast, he said, the traditional values of independent education, as espoused by his organisation, do in fact teach right from wrong, thanks to extra-curricular activities and chapel talks.

This assertion has certainly propelled Mr Walden and his association, which is the educational equivalent of a sort of Vauxhall Conference for minor independent schools, to the headlines of newspapers.

One thing I have learned since becoming a state-school head is that you cannot make claims about your school or any school without having the evidence to prove it. This simple requirement, what the Bush administration witheringly referred to as being “part of the reality-based community”, is enshrined in the Ofsted framework and part of the professional culture of state-school heads. Independent judgments, data, research and evidence must support statements about any school or group of schools, otherwise they are deemed mere ravings.

Such a requirement for evidence does not seem to apply to independent-school heads. They literally make speeches about what they think or feel; they adduce very little evidence of any kind to support their claims. Their utterances remind me of the popular American book of collected aphorisms: Shit My Dad Says, in which the author reports the opinions of his slightly eccentric and opinionated father. That book is intended to provide laughs.

ISA does not commission research and Mr Walden makes his claims based on no empirical evidence. Someone in the state sector could, in imitation of his rhetorical style, similarly and equally falsely claim that independent schools turn out selfish and immoral children.

There are some examples of genuine research about independent education. HMC commissions some interesting and high-quality research on, for example, the importance of the independent sector in keeping certain subjects alive at university level. Classics springs to mind.

But the sector is also a great debunker of empirical research, rather like climate-change deniers. The extensive study showing that pupils with similar A-level results do slightly better at university if they attended a state school is based on the tracking of 130,000 students by the Higher Education Funding Council for England. It is, to quote Al Gore, an inconvenient truth for the sector.

Mr Walden’s speech smacks of desperation. In place of facts, we get assertion. In place of new thinking, we get reaction. In place of reasoned debate, we get name-calling and slander of a sector that educates about 95 per cent of British children. Mr Walden and George Bush are both examples to prove that separation from the reality-based community invariably leads to strategic carnage and reduced political influence.