THE school brought in to improve Addington High has come under fire from education inspectors.
Ofsted has criticised teaching and leadership at Ravens Wood School in Bromley, while an exam board is investigating alleged "malpractice" over school coursework.
The school – which is academy sponsor for Addington High – has lodged a formal complaint about the Ofsted report, disputing its findings.
A statement from Ravens Wood this week said: "We have grave concerns about the professional conduct of the inspection team and therefore dispute the judgements reached."
Jo Tanner, chairman of governors at Addington High, said she remained confident that Ravens Wood could help Addington, despite the Ofsted verdict.
She added: "We are thriving as a school. The support that we have had thus far has encouraged us and enabled us to produce the best results that we have ever seen in terms of GCSEs.
"We remain completely focused for an 'outstanding' from Ofsted within three years."
Asked whether she was confident Ravens Wood could help them achieve that, she replied: "Absolutely."
Ofsted inspectors said not enough teaching at Ravens Wood was good enough to ensure "consistently good progress from all students in all subjects."
They said leaders relied too much on intervention programmes, rather than on improvements "to the daily diet that students receive in lessons".
They added that leaders' and managers' checks on teaching "lack rigour", with too much reliance on consultants.
Governors, they added, had not challenged leaders enough on their assessments of the school.
However, they said pupils' achievement was "good" overall, with most students making "good progress in many subjects".
They added: "Students make good progress in the sixth form because of very stable staffing and sometimes exemplary teaching in many subjects."
The school has been knocked down to a "requires improvement" rating – after "outstanding" ratings at its last full inspection in 2007 and an interim inspection in 2011.
The inspectors visited in June, and their report was published on Tuesday this week.
Exam board Pearson, meanwhile, is investigating the school over an allegation regarding students' BTEC ICT coursework.
A Pearson spokesman said: "We take any allegation of malpractice extremely seriously and will always take appropriate action, in the interests of fairness for all learners, when such incidents are discovered."
A school spokesman said the school was cooperating fully with the investigation.
Ravens Wood was enlisted this spring to share advice, support and resources with then-failing Addington High as its academy sponsor. John Hernandez, who was its deputy head until 2010 and is now head of Norlington Boys, is Addington High's executive head.
School's new rewards scheme for pupils – page 19.
