One of London's most expensive private schools has been downgraded by Ofsted for prioritising teaching “social justice” over "subject-specific knowledge".

Ofsted downgraded The American School in London (ASL), in St John's Wood, from "outstanding" to "requires improvement" after an inspection in December found that teaching places more weight on the school’s "approach to social justice than on learning subject-specific knowledge and skills".

The report said that while the school provided opportunities for pupils with different characteristics to discuss issues affecting them, a significant number felt that their voices are "not encouraged, or in some cases, are suppressed”.

The report praised the school’s music curriculum, which it said was “broad and balanced” but added that “in other areas of the curriculum, the approach is not as balanced”.

“This is particularly where teaching places more emphasis on the school’s social justice programme than on the acquisition of specific subject content,” it added.

Ofsted said that in the school’s lower school curriculum for social studies, pupils “spend much time repeatedly considering identity (including analysing their own characteristics) rather than learning, for example, geographical knowledge”.

The middle school humanities programme was also highlighted for focusing on social issues rather than skills, although the report praised the sixth form curriculum for its “broad and rich range of academic options”.

The school had developed student-led extra-curricular “affinity” groups, some of which limited membership to “under-represented groups”, Ofsted said. It added that some parents and pupils feel this was divisive when seen alongside some teachers’ "stridently expressed views" on social justice.

The report concluded: “While recognising the importance of promoting equalities, a significant minority of parents and pupils told inspectors that a culture has developed where alternative opinions are not felt welcome.

“In some classrooms, teaching has not allowed for questioning or for the balanced presentation of opposing views. Leaders and trustees should ensure that teaching does not preclude tolerance of those with different views, particularly where specific partisan or political views are presented.”

A spokesperson for ASL said: “ASL has been rated outstanding in all of our previous inspections.

“This review, however, was unusual in scope and substance, with a narrow focus on some aspects of our programme.

“Despite meeting 96% of the independent school standards, our rating was downgraded two levels. We do not think this rating reflects the quality of our school or excellence of our teaching.”