Girls are banned from wearing skirts at 40 secondary schools across England as schools opt for gender-neutral uniforms to cater for transgender pupils and to address concerns about female modesty.

The head of one such school said: “The reason for the uniform change initially is about equality, and decency. Our students will all now wear the same uniform. It is a much more decent uniform and it is far less likely to lead to abuse. It is a gender neutral uniform, and we’ve thought carefully about that, ensuring that is was gender neutral.”

He added: “We have transgender students in the school and we have an increasing number of students who are at that crossroads of understanding around their gender. So this uniform removes the need for anyone to make a decision about whether they wear a so-called male or female uniform.”

At another school skirts were deemed “undignified and embarrassing” for staff and visitors when girls sit on the floor for assembly and in drama classes. In Bradford, numerous schools with a high proportion of Muslim pupils do not allow skirts on modesty grounds. Bans are also common in Leeds and Grimsby. In Ipswich, eight secondary schools prohibit them, which means the majority of girls attend “trouser-only” schools.

Pupils at one school are resisting the imposition of the trousers-only policy arguing that a ban on skirts is “sexualising” pupils’ bodies. Its female pupils also argue that they feel more confident in skirts and forcing them into trousers could damage their mental health.

“If any teacher believes seeing a child’s leg is in any way ‘too sexual’,” states the petition, “they should be sacked immediately for gross misconduct.”