We thank Dr MacFarlane for his response^{Reference Griffin, Clyde, Byng and Bewley1} and welcome his comments about various providers and pharmaceutical agencies as well as freedom of speech.

We did not review the neuroscience of brain sex differences but draw interested readers’ attention to a recent review^{Reference McCarthy2} and accessible analyses of available research.^3,4 We agree that the art of psychiatric diagnosis depends on the clinician accepting the truth of the patient's own experience. In the absence of objective diagnostic tests, believing and trusting the patient's own subjective narrative is central to the doctor–patient relationship. However, this starts to lose coherence when the doctor must readjust their own understanding of material reality in order to accommodate another's subjective belief. Declaring that ‘Despite having the body of a man, I am in all other respects a woman’ supposes some inherent essence of gender that many would reject. Reorganising psychiatry to give primacy of gender identity over sex risks breaching the necessary boundaries that exist to maintain the safety and dignity of individuals, groups of people and society more generally.

Without a clear definition of conversion therapy, it is not possible to know the extent of the practice in the UK. Proponents of affirmative care have argued that conversion therapy is anything that might act as a barrier to medical transition.^5,6 It would follow that attempts to assess and treat coexistent mental illness, or even the process of making an accurate initial diagnosis of gender dysphoria, could be described as conversion therapy rather than the basic standard of clinical care that would apply for any other presentation.⁷

The authors remain opposed to any treatment model designed to coercively alter the sexual orientation of bisexuals, gay men or lesbians. It is crucial to distinguish between sexual orientation and gender identity when the latter comes with an expectation for complex, irreversible medical interventions, described as ‘affirmative’. If sustained, long-term benefits of medical and surgical transition could be clearly and independently demonstrated, it would be appropriate to offer these interventions early, but the evidence is not convincing.^{Reference Griffin, Clyde, Byng and Bewley8} Therefore it is reasonable to exercise therapeutic caution, especially in light of growing concerns about complications and regret,⁹ particularly in younger patients.

Given government moves to criminalise conversion therapy in medical settings, the nature of ‘barriers to treatment’ must be clearly described.⁹ New laws will need detailed supplementary guidance for the benefit of patients, doctors and the criminal justice system. We propose that organisations representing clinicians should help legislators make explicit that neutrally framed therapeutic or exploratory work is not conversion therapy, irrespective of how an individual ultimately feels about their own identity.

In the absence of evidence-based guidelines underpinned by solid research, we cannot make recommendations about treatment pathways, and do not advocate one particular model over any other. We draw readers’ attention to the unexplained increase in referral numbers, the higher numbers of children and young people seeking interventions, and the shift in sex ratio,^{Reference de Graaf, Giovanardi, Zitz and Carmichael10} as such demographic changes are significant and deserving of research and explanation. Doctors should ‘first do no harm’. The bar for informed consent to life-changing, irreversible medical and surgical interventions is necessarily high.⁹ Enhanced service provision and new care pathways should be informed by robust research in this patient group.