A secondary school in Brent once praised for outstanding standards has been significantly downgraded by education inspectors - two years after becoming an academy.

In a damning report by Ofsted, Alperton Community School (ACS) in Stanley Avenue, Alperton, has been graded as requiring improvement following its first inspection since its conversion.

The news also comes nine months after Gerard McKenna replaced Maggie Rafee as its head.

The school was judged as lacking in three out of the four Ofsted criterions: Quality of teaching, the achievement of pupils and leadership and management.

The report accused senior staff of not evaluating aspects of the school, such as the impact of teaching on students’ attainment precisely enough, and suggest subject leaders are not skilful enough to improve the quality of teaching “quickly enough.”

It added: “Students’ achievement is below expectations in a number of subjects, including English.”

However, inspectors rated the behaviour of pupils as good and praised the school’s higher than average attendance levels and attainment in maths and science.

The report is a stark contrast to its last inspection in 2011, in which the school was heralded for its good teaching and a responsive curriculum.

Mr McKenna sent a letter out to parents informing them of the downgrade, which said: “I am sure you are aware that Ofsted visited us before half term…they noted our very high attendance and low persistent absence, how we keep students safe and secure and work effectively to deal with bullying, “discrimination of any kind is not tolerated” and “students are expected to be active participants in the school and the local community”.

Ofsted inspectors have come under fire by critics including Policy Exchange, a think-tank who claim it would be better to flip a coin than rely on their judgement.

Jean Roberts from the Association of Teachers and Lecturers (ALT) executive and Brent National Union of Teachers (NUT) secretary, who has lobbied against the formation of academies, told the Times: “This is another example of the fact that becoming an academy does not mean everything will always be outstanding.

“A lot of time and energy was used for the conversion which was basically to get a bit of short term cash in an era when budgets are being cut.”

She continued: “Whether either the ‘outstanding’ or ‘requires improvement’ were or are correct or somewhere in between only those at the school know.”

The Times has connected the school for a comment.