The making of the modern girl part 3: If you want it, go and get it

How do they get what they want?: Today's feisty rebels would make a suffragette blush, but underneath lurk the same old insecurities, says Joan Clanchey

At North London Collegiate school we have just been through the season of interviewing the "rising elevens". With one from a local primary school, I started my routine of warm-up questions with: had she had some home tuition? "Nothing heavy" was the cool reply. I was shaken into a different gear. Her vocabulary asserted itself over my slightly patronising tones: she was dictating the level at which she reckoned our conversation should be pitched.

Twenty years ago was a foreign country; they said things differently there. Recently a new teacher handing back her first set of essays to a class was told by the back-row spokesperson that her style of marking was not very constructive. The remark was probably intended to be constructive in its turn, but it would have been a hanging offence 20 years ago. When I was ranting at a smoker caught in the grounds, she flushed and was as upset about the penalty as she would have been 20 years ago, but when I let my rant move on to the expense to her parents and the exploitiveness of the tobacco company, her flush changed. She said she would accept the penalty but not "the guilt trip".

The social historian Richard Hoggart says that we are living in an age where the Authorities have almost all gone. I suspect women were more conscious of the Authorities than men were: we have always been more dutiful. It is harder to be a teacher in this Post-Authority age, though it is easier to deal with people who level with you rather than people who alternate between being at your feet or at your throat. The assertiveness of girls seems a real phenomenon and its origins seem equally obvious. Girls now know that they are going to work, that they are as employable (more employable?) than their brothers. They see no glass ceiling. Many middle-class girls have mothers with incomes as big as their fathers'. The models for assertiveness are all round them.

I am glad for them but sad for them. I am sad that equal opportunity with men should mean imitation of men. When Sylvia Pankhurst was first trying to get arrested she was recommended to spit at a policeman. She could not do it: her saliva dried up. Today's girls would not have that difficulty, but someone of my generation is wistful about that. I am sad when the feistiness is superficial and is rooted in the old insecurities differently dressed.

The old insecurities seem to me still to lurk. Why else would so many clever, ambitious girls suffer from eating disorders? Why else would so many of them be sure they are the wrong shape? These troubles are more discussed, up-front, recognised than they were, but they do not go away.

A parent at our season of interviewing asked me if our school had a "homogeneous culture". I sifted though a whole selection of answers as I tried to work out the purpose of the question. I was fairly sure that the answer was "No", and I still am. Among our selection of able, ambitious girls there are still all kinds of different assumptions and norms. But the right to speak out and be heard is coming through as one of the strongest common cultures. Provided that the sensitivity to others which women have always had is not lost, then I can do no other than feel rather envious.

The writer is headteacher of North London Collegiate girls' school, a leading academic independent school.