The heads of two of the country’s most successful academy trusts have slammed Ofsted’s new regime – claiming “it is a middle-class framework for middle-class kids”.

Speaking in the Times, Harris chief executive Sir Dan Moynihan and Outwood Grange Academies Trust boss Martyn Oliver claimed the new curriculum focus will “damage outcomes for disadvantaged children”.

The major intervention comes after several Schools Week investigations revealing how schools were rapped for shortening key stage 3. It’s led to scores of schools abandoning three-year GCSEsincluding Harris.

Both trusts specialise in turning around schools in some of the country’s poorest areas. And both leaders criticised Ofsted’s new focus, saying many children – especially the most disadvantaged – need three years to complete their GCSEs.

It is the SW1 approach to education and in a few years’ time will have damaged the outcomes for disadvantaged children

Moynihan told The Times: “It is a middle-class framework for middle-class kids.”

“For many of our children qualifications are all they have in their hands at a job interview or college application and beyond. They have no networks, no contacts, no professional people in their family to help them on in life. Their GCSEs are crucial. Ofsted is valuing curriculum over qualifications.

“The pendulum has swung too far. It is the SW1 approach to education and in a few years’ time will have damaged the outcomes for disadvantaged children.”

His comments come after Harris Academy St John’s Wood, formerly the Quintin Kynaston academy and in special measures when Harris took over in 2017, was rated ‘good’.

The report stated that there were year 9 pupils who do not study history, geography, art or music, adding: “Leaders, governors and trust directors have not ensured that all pupils in Year 9 receive their entitlement to a broad and balanced curriculum that is at least as ambitious as the national curriculum.”

Ofsted claimed this week it has “no preferred length” of key stage three, claiming “it’s not the years … it’s the mileage” that inspectors will look at.

But Moynihan said the St John’s Wood report showed the school was “excellent in every way… but the report makes clear inspectors took issue with the three-year programme for GCSE.”

Martyn Oliver, chief executive of Outwood Grange Academies Trust, added: “Ofsted was trying to solve the problem of exam factories and schools teaching to the test.

“However inspectors on the ground are taking a far too simplistic a view on when GCSE teaching should begin. Many of the children in our schools need a three-year run up.

“They don’t have books at home and space for homework. All that has to happen in school time and disproportionately their life chances come from qualifications.”

Harford told the Times that a “narrowed curriculum has a disproportionately negative effect on the most disadvantaged pupils, who often start school behind their peers and without the benefit of cultural experiences that other children take for granted.

“We have therefore been very clear that we expect to see a broad and ambitious curriculum in all the schools we inspect, and our inspectors will be particularly alert to any signs of curriculum narrowing.”

In September, the Harris trust received its first ever Ofsted rating below ‘good’ or ‘outstanding’.

Inspectors flagged how pupils at Harris Academy Orpington were entered into “inappropriate” qualifications and the number of students leaving its roll was “too high”.

Schools Week had earlier revealed how the trust was entering hundreds of native English speakers in Year 11 into a qualification intended for pupils with English as a second language.