Ofsted's chief inspector has defended single-sex education, just days after the watchdog won an appeal which found that a school's segregation of boys from girls amounted to unlawful sex discrimination.
Amanda Spielman has said that schools practicing "rigid gender segregation should now be on notice that they need to change."
This follows a landmark judgement from the Court of Appeal on Friday which ruled that the mixed-sex Al-Hijrah school in Birmingham - which segregated male and female pupils from the age of nine in lessons, breaks, school clubs and trips - amounted to discrimination.
But the Ofsted boss has argued today that single-sex schools can be justified as they stop girls from "selecting themselves out of some areas of education".
Writing in the Mail on Sunday, Ms Spielman argues that single-sex schools can also help encourage girls and boys to choose subjects that they may not normally choose.
Stop girls 'selecting themselves out'
She writes: "I have been asked how Ofsted can defend the existence of single-sex schools. The easy answer is that single-sex schools are given a specific exemption in legislation.
"But there is a more fundamental point, which is the purpose of the segregation in question.
"If women are to take their full place in a world which is, to some degree, loaded against them, then it is reasonable for parents to choose single-sex schools, to stop girls from selecting themselves out of some areas of education.
"That is why most single-sex girls’ schools emphasise tackling gender stereotypes, and push girls to pursue their interests in ‘typically male subjects’."
'Preparing children for life'
She adds that there is evidence suggesting that educating boys together can reduce the pressure towards gender stereotyping, allowing them to pursue their interests in arts and drama.
"The point is that part of these schools’ purpose is quite explicitly about preparing children for life in modern Britain and our inspections will always make sure this is happening," she writes.
Ms Spielman adds that "good" single-sex schools have opportunities for girls and boys to co-operate and socialise with the other sex through extra-curricular programmes.
She concludes: "The Court of Appeal has made absolutely clear that the notion of ‘separate but equal’ is no defence.
"In that regard Friday’s judgement was not only a victory for Ofsted, but was an even more important one for girls’ and indeed boys’ education."