Lots of girls will remember the uniform policies of their schooldays – being told to button up your shirt was no uncommon thing, and receiving detention for the too-short skirt rolled up even shorter? Well, that was practically a rite of passage. I went to a school with a strict uniform policy that continued into sixth form; no skirt was to be more than six centimetres above knee-length.

In sixth form, although we wore our own clothes, no bare shoulders were allowed. Although I might not have stuck religiously to these rules, I never particularly minded them. I understood: very short skirts were the sort of thing you wore at home, on the weekend – they were fun, casual, and didn't quite fit in with the working environment of a school. I believed the same applied to the no bare shoulders rule - after all, workplaces all over the country have strict rules on dress, and surely, the purpose of the school environment was to prepare you for a professional one. Or so I thought.

One day, in a meeting of the sixth form council, I realised I had long been labouring under a misapprehension. The head teacher was expressing concerns about sixth-formers contravening the dress code; in particular, the number of girls wearing strappy tops. She turned to us and said: "girls, you should remember, these rules are for you. To protect you. We have male teachers and pupils here. We don't want them getting distracted." And just like that, I realised that the uniform policy was no mere set of rules, but a creation borne of a deep embedded sexism: a sexism our own teachers were espousing.

It is only recently that a case like this has made the news. Lord Grey School in Milton Keynes sent 29 girls home for wearing what were deemed to be overly tight trousers or excessively short skirts. Unfortunately, it seems my school was no anomaly; this school too justified their uniform policy by saying it was to protect the girls' modesty. They too were clearly worried about the effect on boys, thereby suggesting that girls wearing short skirts were practically inviting their male counterparts to look up them.

Why is it that in the 21st century we are still thinking like this? The school's comments sparked a backlash, and rightly so. It is not so much that the girls were sent home that is the problem, but that the school is still clinging to outdated ideas of a woman's modesty. It is a shocking word for a school to use: not only is it entrenched in age-old societal perceptions which judge a woman on how she looks, but if girls in short skirts and tight trousers aren't apparently modest-looking then what on earth is the school implying they are?

It seems my school, this school, and I am confident many others, espouse uniform policies for which their justification is not professionalism, but a desire to control women and their bodies. Maybe you think this sounds hyperbolic, but it is not by any means. The idea that by dressing a certain way, a girl is asking to be harassed is a total oxymoron, and yet it is being perpetuated by official bodies. It is quite simple: no girl ever wants unwanted attention – the phrase says it all. For whatever reason she chooses to wear short skirts and tight trousers; it is not that she is looking to become a victim.

Suggesting that a girl is responsible for her own protection through how she dresses is an implicit condemnation of women who do become victims of sexual harassment. It suggests that it is somehow a woman's fault that she has become subject to that kind of attack. It is as though these schools are adopting an I-told-you-so attitude, so that if a female student who was wearing a short skirt, or, as in my school's case, baring her shoulders, was sexually assaulted, she would be responsible, having already been warned about the terrible repercussions of such sartorial choices.

This is utter nonsense, of course – for how can we ignore the fact that the blame for sexual harassment lies squarely on the shoulders of the person who perpetrates it? And finally, who exactly are these people who sexually harass women? I do not know any woman who has not had some experience where she has been catcalled, or groped, or worse. And it never really has a lot to do with how she is dressed. Incidents like this happen all too often. Perhaps this is because of attitudes like those of our schools; our formative environments normalise it.

For a school to say that a girl's clothes will lead somehow inexorably to inappropriate behaviour from males, or to their distraction, implies to boys and men that their sexuality is uncontrollable, and unfortunately, for some men, this attitude is magnified into a belief that they are not responsible for their actions regarding women. Frankly, this is not only a bad message, but an insulting one as well. Most men respect women and think of them as people and not objects, and for them to be told that they aren't capable of doing this in the face of a bit of bare skin is unacceptable.These policies contain within them a misogyny that doesn't just harm women; they are demeaning and detrimental for all of us, regardless of our gender.