After one sex and relationship lesson at Park View School, boys told girls they couldn't refuse husbands sex. A team of 160 students was also alleged by staff to have been appointed as a kind of religious police to report the names of staff and pupils who behaved in "unacceptable" ways, like boys and girls talking to or touching each other. The school vigorously denies both charges.

Clarke also says children were coerced into praying — even though it wasn't a faith school. Clarke cites a teacher using a microphone from a high window to shout at children in the playground after the daily tannoyed call to prayer had gone out (it was switched off when government inspectors arrived).

The Park View Brotherhood weren't motivated just by religious conservatism. Clarke finds there was also a political "Islamist" dimension: anti-Western rhetoric, particularly anti-US and anti-Jewish, "highly offensive comments about British service personnel", and scepticism about the truth of the terrorist murders of Drummer Lee Rigby and American civilians killed by the Boston nail bombers, with links to conspiracy theorist videos about both outrages. 

The Brotherhood was seeking to "impose upon children . . . the segregationist attitudes and practices of a hard-line and politicised strand of Sunni Islam", says Clarke, which "claims to represent and ultimately seeks to control all Muslims".

In the face of such a disturbing picture of extreme and intolerant beliefs, one might have expected universal condemnation from public figures who consider themselves to be enlightened and progressive. So what was the reaction from the former heads of Education in Birmingham, the Runnymede Trust and the National Youth Agency? "A biased mix of uncorroborated smear, anecdote, hoax and chatroom gossip," said Sir Tim Brighouse, Robin Richardson and Tom Wylie in a jointly-signed letter to the Guardian. The evidence adduced was "not forensic" and was "unlikely to bear scrutiny". 

One of the reasons Gove asked Clarke to investigate the Trojan Horse affair was because, as a former policeman, he had a reputation as a patient investigator who understood the difference between hard evidence and hearsay. 

Shahid Akmal, a former Revenue and Customs official, was chair of Nansen Primary governors. What is his view of women — especially non-Muslim women? While acknowledging that women can be as intelligent as men, Akmal considers that "emotionally women are much weaker . . . they are not on the same level". He also thinks they should stay at home to "look after the house, look after the children". He disapproves of women who become "high-flying" politicians: "She has to sacrifice her family, she has to sacrifice her children, she has to sacrifice her husband, all in the name of equality." 

Recorded by an undercover reporter, Akmal also says: "Our women are much, much better consciously in the heart than any white women . . . White women have the least amount of morals."

Equally revealing have been the 3,250 postings from the Park View Brotherhood's discussion group on WhatsApp, a messaging application. Set up and administered by Park View School's acting principal Mozz Hussain, its core contributors were mainly teachers there or at Nansen Primary, or the Park View Trust's other school, Golden Hillock secondary.