A decade ago, two academic papers were published in the Netherlands that changed the way clinicians all over the world treated children who were suffering from 'gender dysphoria' - severe distress about their biological sex.
The Amsterdam-based doctors who produced the papers had for some time been treating a group of children with this condition by giving them drugs that would stop them going through puberty, known as puberty blockers.
That way, if the subjects decided once they reached 16 that they wanted to live the rest of their lives as members of the opposite sex, their bodies would not have already developed the features of their own sex.
These papers presented what became known as the 'Dutch model' - puberty suppression followed by hormone treatment, and then genital surgery at the age of 18 - as solid science.
They claimed that a group of 70 children who underwent this course of treatment, some as young as 11, had grown up to be happy, well-functioning adults. And their early treatment meant they easily 'passed' as the opposite sex - a result which is by no means guaranteed for those who wait until adulthood to take cross-sex hormones and have surgeries.
Clinics elsewhere, including in the UK, copied the Dutch model enthusiastically. Nobody has kept a running total of how many children have been treated according to the Dutch model in the past decade, but it is certainly in the tens of thousands.
In the UK, 2,000 children are estimated to have been given puberty blockers at the Gender Identity Development Service (GIDS) in London, which closed last year after being savaged by the independent Cass Review on gender services for children and young people.
Part of the reason the Dutch protocol became so influential worldwide was due to its claim that it completely healed gender dysphoria, improved psychological function and caused no harm. A miracle cure, you might say.
But now I, and other independent healthcare researchers, have looked more closely at those studies. And what we have found is shocking. Once you take account of the flaws, the supposed benefits all but evaporate, while the harms are hiding in plain sight.
And following the NHS's decision to give the go-ahead to the Pathways study by King's College London, which will see 226 children and young people under 16 prescribed puberty blockers for two years, there's never been a more appropriate time to air our concerns.
At the time the Dutch papers were written, it was already known that children's feelings about being the wrong sex usually disappear by early adulthood without medical intervention.
In the 1980s, a group of Dutch researchers had tracked 879 boys and girls who hadn't yet started puberty. In this sample, 51 of the children, according to their parents, 'behaved like the opposite sex' or 'wished to be the opposite sex'.
By the time they reached the age of 30, however, not a single one of these 51 children had altered their bodies medically to appear more like the opposite sex.
But they were eight to 15 times more likely to have grown up to be gay or lesbian than the other children in the group - indicating that many trans-inclined children's discomfort with their bodies is driven by their as-yet-unrealised sexual orientation.
Other research published since then suggests that the Dutch model of treatment can wreak havoc on developing bodies. It can leave young people with impaired sexual and reproductive function, at higher risk of bone problems and with a potentially lowered IQ. And it appears to lock adolescents into a lifetime of medicalisation.
Yet this incredibly invasive treatment protocol became the norm, simply on the basis that a handful of children might turn out to be grateful later on.
Our analysis of the Dutch studies showed that the claim that the children's gender dysphoria vanished was a statistical illusion. Before they went on puberty blockers, they answered questions about how they felt about their bodies' sexed features, and being treated as a member of their sex.
So the girls were asked how they felt about growing breasts, having periods and being 'treated as a girl', for instance, and the boys were asked about having male body parts and being 'treated as a boy'.
But after treatment the researchers switched the questionnaires. Girls who'd hated being girls were now asked how they felt about being 'treated as a boy' - and of course they said they liked it. Questions about the female physical features they hated were replaced by ones about the male physical features they longed for.
When post-transition female patients said they weren't troubled by unwanted erections (which they were physically incapable of), this was taken as a sign that their gender dysphoria had gone.
This meant the findings were nonsense.
But there was more. When we closely examined the methodology of the puberty blocker study, we realised the final results only included the children who proceeded to cross-sex hormones when they turned 16.
But that left out any whose mental or physical health had deteriorated so much while on puberty blockers that they either chose not to proceed with any further treatment or were advised not to. That inevitably gave the results an artificial boost. And finally, the harms done to those 70 children were brushed under the carpet.
In the case of one male patient, the use of puberty blockers meant that his genitals had remained child-sized meaning there was very little tissue for the surgeon to work with when creating a 'vagina'. The use of bowel tissues as a substitute resulted in an infection that tragically killed the patient.
At least three of the 70 children developed severe obesity or diabetes while being treated with cross-sex hormones - the second step in the Dutch protocol. These individuals were reclassified as non-participants, meaning a large amount of treatment-associated harm was left out of the final analysis.
Another individual appears to have abandoned their treatment before the study ended, suggesting that they had stopped identifying as trans. Several more stopped replying to the researchers' queries, despite being only a year or two post-treatment.
The harms may have continued after the two papers were published. More recent research from the same Dutch clinic, this time looking at sexual function outcomes, reports that at least one other individual died in an apparent suicide.
It's now clear that blocking children's puberty is an experimental treatment with no proven benefits and serious risk of harm.
As researchers continue to seek evidence to support its use, the Dutch clinicians have already moved the goalposts.
They now acknowledge the treatments may not be 'effective' but should still be given because teenagers deserve the 'dignity of risk' and the 'right to regret'.
Such misguided dismissals of the potentially grave downsides should send a chill down the spine of every parent.