A volunteer counsellor with the charity Childline was dismissed after raising concerns about the way some young people are rushed into changing gender.
Former barrister James Esses said he was concerned many youngsters were confused about gender identity and, wrongly, were automatically categorised as transgender or fast-tracked into making life-altering decisions such as undergoing major surgery.
But after sharing his concerns on social media, Mr Esses, 29, claims he became a victim of a belief that young children know their own minds about gender.
First, he was told to leave a five-year degree course because of his 'social media activity'.
Ten days later, Childline told him he could no longer be a volunteer counsellor.
'I just wanted an open and honest debate about a hugely important topic – I'm not sure what is wrong with that,' Mr Esses told The Mail on Sunday.
He is now taking legal action against the Metanoia Institute in West London, where he was studying for a Masters in psychotherapy.
His case comes amid growing disquiet among mental health professionals and parents over the increasing numbers of children and teenagers being allowed to change gender.
Many therapists, argued Mr Esses, fear being labelled 'transphobic' for questioning children's claims they should have been born the opposite sex.
He warned that, rather than receiving therapy to explore any underlying issues, youngsters are often speedily referred for 'irreversible' medical treatments to help them swap gender.
Former barrister James Esses (pictured) said he was concerned many youngsters were confused about gender identity and, wrongly, were automatically categorised as transgender or fast-tracked into making life-altering decisions such as undergoing major surgery
After joining Childline as a counsellor in 2015, he says he noticed an 'increase in the number of young people coming through who said they were in the wrong body. The youngest was about ten or 11.'
Meanwhile, the way some fellow Childline counsellors were handling calls caused him alarm.
He felt they didn't explore properly why children were unhappy with their gender.
Instead, they simply 'affirmed' their belief to be transgender.
Mr Esses said: 'They would just go through the motions of affirming their transition with no form of exploration whatsoever.
'I was shocked that young people were making potentially irreversible decisions about their lives, and potentially irreversible physical and emotional changes, yet no one was willing to have a dialogue about what is the best treatment.'
He felt many youngsters he dealt with seemed to have no real concept of what changing gender actually meant.
He said: 'With the younger children, I realised there was so much they had absorbed from other people, whether it was through online chat rooms or on other organisations' pages.'
He said he became increasingly convinced that 'exploration' of their problems was a better way to help.
'I spent hours with them exploring the underlying causes and other ways of looking at things.
'By the end of our conversation, many decided to wait to see if they could stop hating who they were and perhaps be willing to love who they were.
'That felt hugely important.'
Three years ago, Mr Esses decided he would forsake his job as a civil servant at the Home Office and retrain as a psychotherapist.
He began a course at the Metanoia Institute, which provides training in psychological therapies.
But he soon realised that the world of psychotherapy had embraced the approach that children who say they feel they are transgender should automatically be encouraged to go through the process.
'It was as if there were only universal truths and everyone had to accept them,' he said.
Earlier this year he resolved to make his concerns public.
He was further motivated after learning that the Government was planning to ban conversion therapy, which attempts to change a person's sexual orientation and gender identity.
He feared that such a ban might lead to psychotherapists who help children with gender issues facing prosecution.
So he launched an online petition in May called 'Safeguard evidence-based therapy for children struggling with gender dysphoria'.
Mr Esses regularly takes to Twitter to share his views on gender dysphoria
In one of his tweets, Mr Esses says 'irreversible surgery is not the only option' for children who believe they might be transgender
Mr Esses said therapy 'helps them to find a healthy way to move towards accepting reality of their bodily selves'
Mr Esses says his tweets were deemed to 'bring negative attention' to the Metanoia Institute, where he was studying for a Masters in psychotherapy
However, he was emailed by Metanoia's deputy chief executive Professor Carrie Weston, who said that two members of the public had complained about his 'social media activity'.
He was assured it was nothing to worry about.
The next day, however, Prof Weston emailed again, telling him he had brought 'negative attention' to Metanoia.
His student contract, he says she told him, was 'terminated'.
Mr Esses said: 'I'd been working towards becoming a therapist for almost four years and spent tens of thousands on the course.'
A few weeks later, he says, he was called to a meeting with Childline head Shaun Friel.
He says Mr Friel told him his volunteering contract was being terminated immediately and said: 'It is not appropriate for Childline representatives to use the service to advance their personal campaigns.'
Mr Esses said he was shocked. He'd given 'five years of my life' to Childline, keeping in a logbook each of the 200 shifts and 1,000 hours of counselling he had done as a volunteer for no pay.
He appealed to Childline's directors and to the chief executive of its umbrella charity, the NSPCC, but his appeal was rejected.
An NSPCC spokesman said: 'Volunteers cannot give the impression that Childline endorses their personal campaigns.'
Last night Prof Weston of the Metanoia Institute said: 'When he was a student Mr Esses made a series of public pronouncements.
'In doing so he brought the institute into disrepute and made his position on the course untenable.'
Mr Esses believes the way society is currently debating the issue is a watershed moment.
'This is not just about protecting children, it's also about free speech,' he said. 'If we keep going down this path, people will be far too afraid to say what they feel.
'Children's well-being and free speech are so vital that I feel it is my duty to keep speaking out.'
Visit Mr Esses legal fundraiser here.