National Education Union general secretary Daniel Kebede said: “This is typical of government to put out important guidance in the last week of term, a very busy period for schools.

“We need to remember that what is under discussion is a piece of non-statutory guidance, which is still in draft and out for consultation for 12 weeks.”

He added: “It is also important to underline that schools do not need to change their current policies at this stage.

“Schools work hard to be sensitive, practical, and responsive to the wellbeing of students who are non-binary or questioning their gender identity.”

Paul Whiteman, general secretary of school leaders’ union NAHT, said: “The ongoing delays to this guidance due to political wrangling have been a source of significant frustration, and it is far from ideal for it to be published right at the end of term, after some schools have already broken up for Christmas.

“Upon an initial look, it would appear this guidance leaves a lot of questions unanswered, meaning school leaders will continue to be placed in an incredibly difficult position.”

The Confederation of School Trusts chief executive Leora Cruddas said it was disappointing that the government published the consultation as schools are breaking up.

She said: “This will make it very challenging to respond to any concerns felt by pupils, parents and staff until schools return in the new year.”