Ofsted’s inspections of unregistered schools have uncovered material that says women must not refuse sex to their husbands, and literature calling for the death of gay people.
They contribute to what the inspection body has identified as a threat of children being exposed to extremism in illegal schools.
The Chief Inspector of Schools, Amanda Spielman, said “extremely worrying material” has also been found in poorly performing registered independent schools, and even in a maintained community school.
In a letter to the Public Accounts Committee, she said: “We have, for instance, found books that say it is acceptable for men to use physical violence against their wives, texts that say it is unacceptable for women to refuse sex to their husbands, and literature calling for the death of gay people.
“These texts have no place in young people’s education.”
Ms Spielman gave the example as she highlighted the dangers of unregistered schools which also include “very narrow education” being taught, and the “ability to hide child abuse”.
She said inspectors had been “shocked” by their findings, often in unsafe and squalid premises, with a poor quality of education and in some cases a severely limited curriculum.
To help tackle unregistered schools, Ofsted is calling for a tighter definition of what constitutes a school and for a lower hourly threshold for an institution to qualify.
Ms Spielman added: “Our current lack of powers to seize evidence means that we are tackling this problem with one hand tied behind our back.”
In the letter she described the lack of information about where children who are removed from schools end up as “perhaps my greatest concern as chief inspector”.
“I am not proposing that Ofsted inspects home education, but we must now move to a registration process run by local authorities,” she said.
In the letter she also branded the existence of around 490 “stuck” schools – those that have had poor performance for a long time – as “nothing short of scandal”.
She said: “That these schools remain poor for so long means that, for some children, in certain areas, there may be no opportunity to attend a good school at any point in their education.
“This is nothing short of a scandal and is a betrayal of children’s futures.”
Ms Spielman wrote that while “funding is a major topic of concern in the sector… inspectors are not seeing an impact on education standards”.
But she continued: “Where we do have clearer evidence of a decline in the quality of education are in the narrowing of the curriculum in schools and an endemic pattern of prioritising data and performance results, ahead of the real substance of education.”
She said research had found evidence that an overly data-driven system is limiting what pupils are able to study and learn.
Ms Spielman further said she had concerns about the risk that removing children from a school’s roll presents.
She said the illegal off-rolling of pupils, driven by a desire to boost results, is not acceptable in any circumstances, adding: “Such an approach harms children for life.”