Sarah, not her real name, says she was sexually assaulted in her classroom by a fellow pupil.
She says the boy later threatened to kill her. But when she reported it, she claims the school put reputation before good practice and failed to deal with her allegations properly.
Sarah, now at university, told her story to Sky News but she is also among 240 current and former pupils of Highgate School in London who have written an open letter detailing allegations of abuse and misogyny.
Some accuse the school of covering up a "rape culture".
Sarah told Sky News: "There was this boy, and he would constantly message me and send me explicit pictures and I never responded."
She said this was fairly "normal" behaviour in the school, so she put up with it, but the boy continued to pester her, sit next to her in class and sometimes touch her leg.
She said it then escalated: "In class, this boy, while my teacher was there, under the table, slid his hand all the way up my skirt – I yelped and got up and ran out of the classroom."
She later made an excuse to the teacher as to why she left, but the harassment continued by text.
"I was sitting in a Spanish lesson when he messaged me saying – I’m going to kill you – I will end you unless you come here now."
At this point, Sarah decided to report him.
"When I told my school, I told them everything that happened – and they essentially twisted everything I told them against me.
"They took CCTV footage of me at a time when he grabbed me towards him, and they saw I was laughing and said well you’re laughing in this video, so we don’t believe anything you are saying."
Sarah said the boy did eventually receive a punishment for his behaviour, but she feels it didn’t reflect the severity of the crime, and he remained at the school.
She said Highgate, which charges fees of £21,600 a year, was worried about how things would look.
"The school is obsessed with their reputation. And they would rather have everyone think nothing like this would happen and find ways to twist it on you, rather than actually acknowledging and punishing that boy for what he did."
But Sarah also admitted with some despair that her friends, despite sending her messages of support now, didn’t stick up for her at the time, when their testimony would have helped.
An ‘anti-snitch’ culture among children is something former pupils recognise as part of the problem; that teachers can’t amass information when there is a wall of silence.
Kaitlynn Mendes, professor of gender, media and sociology at the University of Leicester, said: "Younger people have a much easier time reporting adult strangers for these kinds of practices, than their own peers, because there are certain dynamics.
"They don’t want to rat them out, they don’t want to become unpopular because they report on someone else, so that’s a challenge."
Highgate is one of many leading schools that have been named in more than 10,000 anonymous sexual abuse or harassment allegations posted on the website Everyone’s Invited. None of these allegations can be verified.
But Sky News spoke to another former student from Highgate School who doesn’t want to be identified. She said the misogynistic culture began early and that, aged 11, the girls in her year were ranked by the boys using an online app.
Nicola told Sky News: "I remember when I was in Year 7, looking at a boy’s Ask FM account and he’d been asked to rate every girl in his class, and I remember I was rated the lowest of all the girls in the class, and I was so upset by it.
"I told my mum, and she told the school and the school said they knew that boys had accounts on Ask FM, they knew that this happened, but they didn’t reprimand the boys or anything."
Nicola believes this sent out a message to boys that it was okay to objectify the girls. When she was a bit older, at parties, the boys would get points for the number of girls they kissed, but negative points for kissing the ones ranked as ugly.
She said: "There was this ‘boys will be boys’ mentality about it, where boys were allowed to treat us how they wanted. They could make us upset in class, on the internet, and they were never told off for it."
This "me too" moment for pupils has snowballed to other schools in the state sector and to universities, and on Wednesday the government announced a new dedicated support helpline and a review of safeguarding policies in schools.
Responding to the allegations, Highgate School said: "At Highgate, pupil wellbeing is at the heart of all our thinking.
"We treat any allegation of sexual assault and rape with the utmost seriousness. No victim of sexual harassment or abuse should ever be silenced and we are clear of our statutory safeguarding obligations as a school.
"Where allegations are made we follow safeguarding guidance, support the pupil and make referrals to the relevant authorities including the police and the local authority MASH (multi agency safeguarding hubs).
"We are committed to an external, independent review of all these extremely serious allegations, led by The Rt Hon Dame Anne Rafferty DBE PC. We are encouraging all of our pupils, past and present, to share their experiences or to give feedback to the school anonymously.
"Their comments, together with input from the pupils’ anti-sexism group, have been channelled into our anti-sexism and sexual violence plan, which is being developed in consultation with our school community and external agencies."
Alleged victims say more needs to be done to address an underlying tolerance, which they believe has cultivated poor behaviour among some pupils.