This week’s downgrading of Manchester’s King David High School from outstanding to inadequate — from the top to the bottom Ofsted grade — shows how far equality law is biting into religious education.

Inspectors said the Orthodox academy had doubly discriminated against pupils in its religious Yavneh streams: by offering them a narrower secular education than pupils in the school’s general section and giving girls less opportunity to socialise with boys.

Now the school is mooting an appeal to the courts. “The legal arguments are very strong,” said King David chairman Joshua Rowe this week. “This is the likely option.”

Faith schools had once assumed they were free to organise their religious education as they wished.

But an Appeal Court ruling in 2017— against a state-aided Muslim school which kept boys and girls completely apart — indicated otherwise.

As a result of the ruling, the Hasmonean High School in London, which teaches boys and girls on different sites, has split into two single-sex schools.

Another Manchester school, the Strictly Orthodox Yesoiday Hatorah primary, which had separate classes for boys and girls, is planning to divide into two schools.

Unlike the school at the centre of the Appeal Court ruling, girls and boys were not entirely segregated at King David. The school says it received assurances last year from the Department for Education via Pajes — the Jewish Leadership Council’s schools network — it was complying with the law.

The school’s set-up, which has been in place for close to 30 years, was intended to attract more religious families and ensure King David had sufficient numbers of pupils to sustain it.

But although King David may be unique, the implications of the Ofsted verdict could go further. Any Jewish school which, for example, teaches Talmud to boys but not to girls now seems vulnerable to an adverse finding.

Leaders of schools which practise segregation could be rated inadequate, Ofsted warns in its new handbook, which is due to come into effect in September.

Mr Rowe is in no doubt the King David report reflects a wider agenda driven by Ofsted chief inspector Amanda Spielman’s belief in “muscular liberalism”.

The inspectorate, he believes, needs to be reined in. “Ofsted rules the roost. They make the law rather than follow the guidance from the Department for Education and they are not answerable to anyone.”

But in the meantime the school is considering options. It could “demerge” into three distinct schools run under one academy trust: Yavneh boys, Yavneh girls and King David.

The Department for Education may be sympathetic in the circumstances, even if the two Yavneh branches ordinarily might seem too small to become separate schools.

But simply appealing to the DfE to overturn the Ofsted judgment is out of the question as ministers do not have the power to do so.

Another option would be to persuade the Education Secretary to tweak the law so that King David’s arrangements would be exempt from the equality law in the same way that single-sex schools are.

As Mr Rowe points out, the logic for doing this is strong. However, with a Brexit-affected backlog of legislation already, even a government amenable to the idea might struggle to find time to do this.

So taking Ofsted to court may be the only practical option.