Wanstead High School has slipped from being a good school to one requiring improvement, according to Ofsted inspectors.

The education watchdog said that while teaching is "strongly improving" and pupils behaved well, it was concerned that students were not making good enough progress academically in some subjects.

It comes following a visit by seven Ofsted inspectors to the secondary school in April, with their report published on Tuesday.

While progress in English, Maths and Science was all said to be good, Ofsted said some other lessons were lagging behind at both the school and its sixth form.

Inspectors said "too many" books were not marked regularly or in enough detail, and that in some lessons there were not opportunities created for students to learn and discover knowledge independently of teachers.

The report also said the school's leadership needed to be more rigorous in managing its teachers.

But they praised Wanstead High's wide range of sporting, musical and cultural activities, saying they helped to develop pupils well.

Ofsted also found that bullying was rare and well dealt with, and that governors did a good job of scrutinising many aspects of the school.

The report described the school's environment as "calm and purposeful".

Inspectors said: "It is a friendly and welcoming place for staff, students and visitors. Students get on well together and are courteous, considerate and caring.

"Students’ behaviour is typically good in lessons and around the school. Disruption to learning is rare."

But the report added: "On entry to the school, students’ skills in reading, writing and mathematics are at least average and often better.

"[But] Their progress varies across different subjects and in year groups, this being the reason why achievement requires improvement."

Inspectors said there was some good and outstanding teaching, but in some cases "students are less engaged as a result of teachers talking to the class for long periods and not taking sufficient account of their different abilities when setting them work."

Wanstead High, in Redbridge Lane West, was previously rated satisfactory in 2005 but managed to improve and achieve a good rating following its last inspection in 2008.

Headteacher Chris Van Bussel, who has been in charge throughout this period, said he believed Ofsted's new and tougher approach to grading schools was part of the reason for the drop in its rating.

He said: "When you read the report in full you find there is much that is very positive.

"It does note that there is good or better progress in the majority of subjects, just not in all areas, which is something we need to improve.

"It says that at the end of Year 11 the attainment of our pupils is above average, so the report does seem a bit contradictory in places.

"Obviously I'm disappointed [in the drop from a 'good' rating] but in January a much tougher criteria was introduced by Ofsted and the bar has been raised.

"I think now that we know the criteria better I strongly believe when it comes to our next inspection we can be rated good or outstanding.

"I also think it's a great positive that in the survey with parents 91 per cent said they would recommend the school".

More than 1,500 pupils attend the school, with a further 360 students at its sixth form.