In a test case that could pave the way for similar legal challenges, the governors of Crown Woods school, in Greenwich, will ask a judge to reverse the April decision to put it in special measures.
On November 30 they will argue at a judicial review hearing that a report by the Office for Standards in Education was unreliable because the inspection team saw so little of the school's work.
Over two days, four inspectors sat in on 64 classes, seeing, the school claims, less than 3 per cent of weekly lesson time. In some, they say, the team spent only five or 10 minutes watching teachers.
OFSTED normally sends a team of around 15 inspectors to look at between 10 per cent and 15 per cent of lessons over a period of a week.
A spokesperson for Greenwich said: "The governors believe that such a harsh judgment is unfair.
"They do recognise that the school has some weaknesses and, since the inspection, the staff ad governors have been working closely with Greenwich council's own inspectors to produce an action plan. The council is giving the school its full support in the quest for improvement, and the target is to achieve this transformation within a year."
The school is London's largest secondary, with 2,100 pupils. Next year, it will be taken over by a new headteacher, Michael Murphy, who will become the highest-paid head in the state sector with a salary of pound;92,000.
He is currently on pound;85,000 as head of Hurlingham and Chelsea school. Over the past six years there, he has raised the proportion of pupils getting five good grades at GCSE from 6 per cent to 27 per cent and nearly trebled the roll to 1,100.He has promised to tackle Crown Woods' pound;250,000 budget deficit and improve the school's examination results. Last year, only 30 per cent of pupils achieved five or more GCSEs at grade C or above.
A spokesperson for OFSTED said: "We believe we have sufficient evidence to place the school on special measures and we stand firmly by our decision."