Primary school boys should be allowed to wear tutus and high heels if they want to, the Church of England has said in its first guidance for teachers on transgender issues.

Children should not be restricted by their gender when dressing up, and girls should be able to wear a tool belt and fireman's helmet if they choose, the document says.

The guidance for teachers in Church of England schools, endorsed by the Archbishop of Canterbury, says that children "should be at liberty to explore the possibilities of who they might be without judgement or derision".

The document comes as a growing number of children coming forward to express doubt about their assigned gender.

Figures released earlier this year by the Gender Identity Development Service show that the number of under-18s referred to the north London clinic has grown from 314 in 2011 to 2,016 last year.

The guidance says: "For example, a child may choose the tutu, princess’s tiara and heels and/or the fireman’s helmet, tool belt and superhero cloak without expectation or comment. Childhood has a sacred space for creative self imagining."

The document, which gives teachers guidance on how to challenge transphobic bullying, also says young children "should be afforded freedom from the expectation of permanence.