The number of children in Sheffield being excluded from school for sexual misconduct has shot up over the past year, new figures have revealed.
Campaigners have warned that a failure to take sexual assaults in schools seriously enough could have been masking the true scale of the problem.
The warning comes after a hike in the number of exclusions for sexual misconduct across the country.
In Sheffield, schools handed out 49 exclusions to children who had engaged in sexual misconduct in the 2016-17 academic year, according to data from the Department for Education.
This was an increase of 40 per cent from the previous year, when 35 such exclusions were recorded.
Although the school population increased over the same period, the rate at which sexual misconduct-related exclusions increased was higher than the rate of population growth.
This means cases were far more prevalent relative to the number of school children than they were a year ago.
According to Sarah Green, co-director of campaign group End Violence Against Women, the Government has for too long failed to implement a proper system for monitoring, documenting and dealing with sexual abuse between school children.
She said: "There’s been a culture of minimising this behaviour and difficulty taking it seriously.
"It is critically important to have this data recorded. We must know the levels of sexual harassment and assault in our schools.
"Adult women shouldn’t have to put up with it in the workplace, but girls at school are told it’s just what boys to, and serious assaults aren’t taken seriously.
"Girls must never be expected to tolerate harassment, and assaults should be dealt with immediately and seriously."
While the group has welcomed recent plans for enhanced sex and relationships education, they argued that the plans don't go far enough and may leave room for parents to be able to withdraw their children from the lessons.
The picture in Sheffield mirrors the national trend, with the number of exclusions jumping by 9 per cent in 2016-17 to 2,340 cases.
Prior to this, the number of cases had been gradually coming down from a high of 3,450 in 2009-10 - the earliest year for which comparable data is available - save for another spike in 2014-15.
In Sheffield, the highest number of cases was in 2014/15, when it reached 40 exclusions.
Sexual misconduct includes cases such as sexual assault, abuse and harassment, but could also include behaviour that is not directed towards another pupil, such as lewd behaviour.
Although exclusions for this specific offence are not broken down by sex, boys accounted for the vast majority of overall exclusions in England.
Nationally, most of the exclusions were in secondary schools, although some were in primary and special schools.
A spokeswoman for the Women's Equality Party agreed that better compulsory sex education was needed in schools.
She said: "What more evidence do we need for compulsory sex education in schools, which includes lessons on consent and no opt outs?
“Along with these lessons, young people need media analysis skills to see the ways they are bombarded with gender stereotypes and the objectification of girls and women."
A spokeswoman from the Department for Education said: "It is vital every child understands the importance of healthy relationships and have the confidence to say no, or to recognise when someone else has not given consent.
"That is why our new Relationships Education in primary schools and Relationships and Sex Education in secondary schools will teach pupils the building-blocks and then concepts of consent in an age-appropriate way, with the knowledge on how to form healthy relationships.
"We have also provided new guidance for all schools and colleges on sexual violence and sexual harassment between pupils, including how to support young victims.”