Holland Park school has already suffered disputes between head Colin Hall and a group of teachers and parents who fear he is abandoning the progressive traditions of the first purpose-built comprehensive, founded in 1958.
Now, as the west London school, which counts Tony Benn, Shirley Williams and Vanessa Redgrave among its former parents, prepares for an inspection at the end of the month, new concerns have emerged.
Staff have warned through the National Union of Teachers that discipline is deteriorating, while parents claim school management has made the situation worse with an over-authoritarian response.
A spokesman for the NUT, the main union at Holland Park, said teachers had called special meetings to discuss concerns over pupil behaviour.
He said in one incident a female member of staff had been punched by a pupil in a corridor.
"Long-serving staff are noticing an increase in the frequency of serious verbal abuse and the number of fights, and there have been some physical assaults on staff," he said.
The school said it had experienced three "serious" incidents during the past term, but said behaviour was "broadly in line with previous years".
But a spokesman for the school confirmed the past year had seen an increased police presence, the introduction of security guards, locked gates, an extension of its CCTV system, and - in an experiment, since abandoned - pupil toilets kept locked during lessons. "It is not authoritarian to take measures to improve our school and protect our community. From our perspective they seem to be straightforward, commonsense steps taken against a background of growing problems in a wider society."
The Rev Michael Sawyer, chairman of Holland Park School and Community Association, said: "Behaviour has got worse over the past year so in that time we have had security guards and cameras and there are concerns about how that is being resolved."
A father who wished to remain anonymous said: "What is alarming with these kind of measures is that they are meeting force with force and authoritarianism makes its own problems."
Violent pupils, 19