DEPTFORD Green School, which moved into a new £32m building last summer, has been put into special measures by Ofsted.
In a scathing report, inspectors judged pupil achievement, quality of teaching and leadership at the Edward Street school in New Cross to be inadequate. Pupil behaviour and safety also required improvement.
Lewisham Council has now appointed Bob Ellis, credited with turning around the fortunes of Conisborough College in Catford, to be the school's executive head teacher.
A January inspection at the school showed that Deptford Green's results were in decline and student progress in maths was poor with "not enough good or better teaching to overcome students’ past underachievement in mathematics."
Inspectors also wrote that the governors had "not been effective in holding the school to account" and that improvement had been held back, partly because of a large turnover is the senior leadership team.
Last year, just 46 per cent of students gained five or more A* to C grades at GCSE including English and mathematics, compared with 54 per cent in 2010.
Mr Ellis, who will continue to lead Conisborough alongside Deptford Green, said: "The Ofsted inspection that took place in the spring term has given the school a clear focus on the areas that need to be addressed.
"The staff, students and their parents are committed to ensuring that Deptford Green School provides an outstanding service to our community."
He added: "At Deptford Green we enjoy access to the best educational facilities in London and we are determined to use this investment to secure the very best outcomes for our students."
A spokeswoman for Lewisham Council said: "We acted promptly in response to the Ofsted judgement and there is already new leadership at Deptford Green School that we are confident will prove effective very quickly."
The school will now undergo regular monitoring by Ofsted inspectors.