Debate has been raging in the United States, partly thanks to campaigning by Leonard Sax, a paediatrician convinced that boys’ attention problems are caused by education not being tailored to their needs. The Bush administration has also expressed interest in creating more single-sex schools. But the US situation is very different: the country has little recent history of single-sex state schooling, and laws barring sex discrimination in education have made experimentation difficult.

As ever, the debate is more low key here. Single-sex state schools were common until the 1960s, since when numbers in the UK as a whole have dropped from nearly 2,500 to around 400, Most are fiercely supported by parents: many, especially girls’ schools, top exam tables south of the border. Independent schools, traditionally single sex, are going mixed more slowly. Meanwhile, some mixed comprehensives are going the other way, experimenting with segregated lessons to see if results improve.

Here Professor Alan Smithers has taken a long, cool look at all the research and concluded that there is no discernible educational benefit from single-sex schooling. Nor is there a benefit from coeducation, he has found. In other words: take your choice (he chose single sex for his own girls). It ought now to be choice unencumbered by false expectations.