Ms Stern said she was in talks over a documentary “but when I started to take these positions, the discussions stopped, and I lost a lot in my personal life too. I lost some of my dearest friends”.

“But I don’t regret it because I don’t think I could have done otherwise. I felt it was the right thing to do morally and ethically,” Ms Stern added.

Censored and criticised

Down but not out, they decided to investigate the transgender universe in depth and write a book about their findings.

While sales have surged, they say they have been censored by many French bookshops and attacked by Paris’s Socialist town hall, which pressured the capital’s billboard company JCDecaux to pull posters advertising the book.

“Sexual orientation and gender identity are not an ideology”, said Emmanuel Grégoire, Paris’s deputy mayor, for whom “the dissemination and promotion of such discourse runs counter to the values espoused by the city of Paris”.

“Transphobia is a crime. Hatred of others has no place in our city. Paris must not be used as a platform for this intolerance.”

Ms Moutot denounced “an act of censorship based on suppositions rather than on an analysis of the content”, as well as an “obscurantism that seeks to muzzle all critical thought”.

“Our book is not transphobic, and in no way does it advocate hatred of others or of trans people”, she added, describing it as a “well-sourced investigation” into “certain players who push gender transitions and make money from them”.

Accused of inciting hatred

The pair have been sued for “incitement to hatred” by two LBGT+ rights groups, including SOS Homophobie, which has received €350,000 in funding from Paris and “has hijacked the struggle of women to submit to trans dogma”, they assert.

Ms Moutot has also been charged with “incitement to anti-trans hatred” after appearing on a chat show in 2022 beside France’s only trans local mayor, Marie Cau, who she refused to call a woman and instead described as a “trans-feminine male”. She faces a four-month suspended sentence. Ms Cau has likened the authors to “Nazis”.

“If I’m found guilty, it’ll be the last straw, I’m leaving France,” said Ms Moutot, who added that the art of “contradictory debate”, once a source of Gallic pride, was in danger of dying out.

Last Sunday, a group of leading French figures released a tribune slamming their work as “hate-filled” and “promoted by the whole of the political far-Right’. Diane Ouvry, the book’s publishing agent, is also press attaché to hard-Right polemist and politician Eric Zemmour.

Signatories included Left-wing parties, Nobel-prize-winning author Annie Ernaux and publisher Vanessa Springora, who penned Consent – a landmark post #Metoo book on how she fell under the sway of French author Gabriel Matzneff as a child and had underage sex with him.

Ms Moutot said it was ironic that Springora, a staunch defender of child protection, failed to see parallels with minors “consenting” to sex reassignment surgery, only to regret it later.

Support from Rowling

On Sunday, chants calling for Ms Moutot to be thrown into the Rhine in the Strasbourg protest – one of several around France against “transphobia” – were picked up on by Ms Rowling.

“As someone whose death has been demanded on placards for exactly the same reason (knowing ‘woman’ isn’t a feeling in a man’s head), I send @‌doramoutot love and solidarity,” she tweeted to her 14.1 million followers.

“I admire her for her courage. I agree with everything she says. She must have had a very comfortable life before, which is not at all the case now,” said Ms Stern.

“She got the same treatment as we did. When we realised that an international figure like that was getting such a pummelling by the French media, with so little nuance, we knew what to expect.”