A number of private Christian schools have threatened legal action after having their status downgraded by education watchdog Ofsted, partly for failing to “promote respect” for LGBT people and British values.

Dozens of schools in the UK follow the Accelerated Christian Education (ACE) curriculum, a Christian fundamentalist course of learning that grew up in Texas, before expanding to other countries. ACE currently lists 27 UK schools on its website.

Concerns have been repeatedly flagged about the use of ACE in British schools in the past, with an investigation in 2014 raising concerns about ACE textbooks teaching that homosexuality is a choice, evolution is a lie, abortion is wrong, and AIDS can be avoided by following the Bible.

Ten ACE schools affiliated with Christian Education Europe network have this week threatened legal action, after Ofsted inspection results that saw them criticised for failing to meet rules on teaching ‘British values’ that were introduced by former Education Secretary Nicky Morgan.

After simultaneous visits by Ofsted in October, nine of the ten schools were declared ‘inadequate’ or ‘requires improvement’, with many of the reports citing evidence that pupils were not taught about other religions, while inspectors to some schools also warned of a failure to “actively promote respect for people within the protected characteristics groups” due to rife homophobia.

The report for inadequate-rated Luton Pentecostal Church Christian Academy notes: “The school’s policy statement on personal, social and health education states: ‘Whilst we understand that the government has redefined marriage we will actively promote exclusive heterosexual marriage and celibate singles, as God’s gift and design; and as such the best way toward human happiness and fulfilment, but will discourage intolerance.’ This statement describes an approach that is too far removed from the active promotion of respect for gay and lesbian men and women.”

The report for the inadequate-rated Windsor King’s House School also noted: “The proprietor must provide personal, social, health and economic education which encourages respect for other people, paying particular regard to the protected characteristics set out in the 2010 Act.”

The schools have threatened legal action, via the Christian Legal Centre.

Andrea Williams of the Christian Legal Centre, who has previously defended gay ‘cure’ therapy, vowed to fight the rules.

She told the Times: “These schools produce children who are kind, tolerant, interesting and go on to do good jobs. Most of all, they are happy.

“That is what Christian education does for them…. Those not following the political ideology of Ofsted are now liable to be punished.

“Ofsted is critical of the Christian belief system within the schools and yet it is this very belief system that is the foundation of schools across this country.”

Jay Harman of the British Humanist Association said: “We have been raising concerns about these schools in the media and with government for years, and we’re glad that the authorities are finally beginning to realise how badly the children within them are being failed.

“The line Ofsted has taken here is absolutely right, and it is frankly astonishing that any school could accuse inspectors of unfair treatment while providing children with a narrow, doctrinaire, and homophobic curriculum.

“It is essential that inspectors do not become discouraged by these disingenuous claims and we will continue to support both Ofsted and the Department for Education as they rightly toughen their stance against this kind of teaching.”

The requirement for Ofsted to test all schools on ‘British values’ including tolerance for minority groups were introduced by former Education Secretary Nicky Morgan in 2014.

At the time, Mrs Morgan came under heavy fire for the plans, which included handing Ofsted inspectors powers to downgrade schools that fail to comply with the Equality Act, with a requirement to “actively promote” tolerance.

Mrs Morgan said at the time: “I’m afraid I have no sympathy for those who say that British values need not apply to them, that this should purely be a special test for schools in predominantly Muslim communities or our inner cities.

“Every school regardless, faith or none – should be promoting British values, because it’s the right thing to do. A commitment to British values means that we also hold to account those schools where girls are made to sit at the back of the class, where homophobia goes unchecked, where young people aren’t being made aware of the many facets of British culture.”

At the time, the Department for Education insisted: “Ofsted are rightly ensuring that schools do not indoctrinate pupils about gay people – or any other people – being inferior.

“The same goes for schools that do things like make girls sit separately at the back of the class. Both are practices which go directly against the fundamental British values of tolerance and respect.

“We believe schools should prepare all pupils for life in modern Britain. A broad and balanced curriculum is vital for this.”

Ofsted said the schools “have a responsibility to prepare pupils for life in multifaith Britain and are expected to provide a broad and balanced curriculum, which teaches respect and tolerance towards those from cultures and faiths that may not be represented within the school.”

Earlier this year, an undercover reporter for VICE found that an ACE school in the UK offered to help perform an exorcism-style ritual for a gay pupil.

Pupils in ACE schools do not study towards GCSEs or A-Levels, and instead work to attain a International Christian Certificate of Education.