Like many European nations, Britain has debated how to assimilate minorities while maintaining freedom of religion. One issue is the extent to which schools should tolerate symbols and clothing associated with religious beliefs, such as Muslim head scarves. In British schools, much discretion remains with head teachers.

Last year, the Birmingham City Council received an anonymous document outlining a plan called Operation Trojan Horse, in which fundamentalist parents would raise concerns about the staff and curriculum — particularly over issues like sex education — infiltrate the governing bodies of the school and then promote a leadership sympathetic to their views. It is unclear what steps schools took in response to the document, and several government bodies are looking into the case. In all, 21 schools are being investigated over claims that male and female pupils were segregated, that sex education was banned and that, in one case, a cleric linked to Al Qaeda was praised in a school assembly.

While one leaked report from school inspectors appears to have flagged concerns, evidence of a conspiracy is scarce. According to news reports, the leaked report from the Office for Standards in Education, Children’s Services and Skills, or Ofsted, detailed several criticisms of one school, Park View, and said it had done too little to warn pupils about the dangers of extremism.

Image Theresa May Credit... Peter Macdiarmid/Getty Images

The issue spilled over into Mr. Cameron’s cabinet last week in a briefing published in The Times of London, which the prime minister’s office now acknowledges came from the secretary of state for education, Michael Gove, suggesting that the department of the home secretary, Theresa May, had been too tolerant of the efforts by hard-liners to infiltrate the Birmingham schools for fear of being seen as Islamophobic.