A private school says it is investigating claims teachers forced girls to kneel on a cathedral floor to measure the length of their skirts.
The anonymous allegations were revealed on whistle-blowing website Everyone's Invited, The Telegraph reported.
The post said female teachers were "enforcing the blatantly sexist rules".
Head teacher Gareth Doodes said the claims were being looked into and safeguarding procedures had been started.
"Any allegation that is made to us we take very seriously as I'm sure every school in the country is doing so that's been mentioned on the Everyone's Invited website," he told the BBC.
"So immediately that I heard we'd been mentioned on that website I informed the safeguarding lead to look into it and we're going to look into our procedures and our practices.
"Now I've only been headmaster here since September and I don't know first hand of this happening and I haven't witnessed it.
"That doesn't mean to say it may have happened before, and therefore we're going to investigate it as every school should do so."
Students at the school had recently set up a group to look at attitudes towards women and girls, in light of the death of Sarah Everard, attacked while walking home in Clapham, London, last month.
The Change the Narrative society aims to address sexist and misogynistic behaviour towards women, pupil Alice said.
She said it was "a safe place for members of the school and to discuss important issues".