It is every headteacher’s nightmare - “inadequate”: the ultimate Ofsted damning judgement that could see them out of a job and their school turned into an academy.

However, a surprise High Court victory by one of the most country’s most controversial schools could give hope to others that have been branded “inadequate” and left to deal with the verdict’s damaging consequences.

Lawyers are already warning that the ruling could have serious consequences for the government’s academies policy. Heads’ leaders are expecting scores of schools to take legal advice as a result.

The case involves Durand Academy, based in Stockwell, south London, which has made national headlines because of its former head Sir Greg Martin’s total salary of almost £400,000, the creation of a private leisure centre on the school grounds, and its prolonged battle with the Department for Education over its complex governance structure.

Ofsted added to the pressure on the school when it sent in inspectors late last year. It was, Judge Martin McKenna says, a “fraught” inspection, and the resulting draft report recommended that the academy be put into special measures.

After the school mounted a High Court challenge, McKenna quashed the report last week. He based his decision on Ofsted’s complaints procedure, which does not allow any “inadequate” school’s judgement to be changed. It is, he says, “not a rational or fair process”.

In the hours after Tes broke the story, social media was alight with speculation about the implications of the ruling.

Would Ofsted overhaul its complaints process? Would all special measures judgements be quashed? Would Ofsted have to halt inspections until it had addressed the judge’s concerns?

‘Window of opportunity’

For one education lawyer, the biggest impact of the ruling could be on the government’s academisation programme.

Since the Education and Adoption Act passed last year, all schools that are rated “inadequate” must legally be turned into academies. Matthew Brotherton, a partner at Stone King law firm, believes “it opens up a window of opportunity” for schools that have been subjected to an academy order but are yet to be converted.

“When those schools that have been inspected and put in special measures and then the department has relied upon that to make an academy order, I would query whether that gives them grounds for challenge,” he adds.

For schools that have already been converted on the back of an Ofsted report, he believes it is too late. But Brotherton says the judgement does give schools who have an unpublished “inadequate” report “fertile grounds” to challenge the inspectorate.

The big barrier for most schools taking legal action will be the expense. Durand said that legal costs for its dispute with Ofsted amounted to £300,000.

Brotherton believes that it could be done for less, but still estimates a minimum bill of £20,000 for schools that want to challenge their reports.

‘Need for self-protection’

Ofsted says that “it is too soon to know what the implications are for other providers” but it says it will keep it under “close review”.

It is seeking to overturn McKenna’s ruling. A spokesman says: “We will continue to carry out school inspections as scheduled regardless of the decision on our application for leave of appeal.”

The inspectorate also says it needs “proper time” to review whether its complaints procedures require what its terms any “clarification”, without elaborating on whether this would lead to rewriting the actual policy.

Geoff Barton famously had his own run-in with Ofsted after Hardwick Middle School in Bury St Edmunds was rated “inadequate” while he was executive headteacher.

In a Tes article cited in Durand’s legal arguments, he wrote that “the Ofsted complaints procedure too often seems constructed around a deep and dutiful need for self-protection”.

Now general secretary of the Association of School and College Leaders, Barton describes the court ruling as “a very significant moment”.

“If I was at Ofsted, I would be very hastily looking at what the implications could be,” he says. “It might be that we find in September a whole range of schools that say: ‘If it applies to Durand, it applies to us as well.

“I suspect that if this was not the holiday period we would have had 40 phone calls from schools asking our lawyers about this.”

The DfE was contacted for comment.