This inquiry is aimed at finding out whether these treatments are beneficial for the mental health of adults suffering from gender dysphoria.

NHS England has announced that it is setting up a review of how the seven specialist services operate and deliver care after past and present staff shared misgivings privately during a previous investigation.

As a first step, NHS England will send “external quality improvement experts” into each of the clinics to gather evidence about how they care for patients, to help guide the inquiry’s direction.

The move follows the publication on Wednesday of a landmark review by Dr Hilary Cass, a former president of the Royal College of Paediatrics and Child Health, which recommended sweeping changes in the way that the health service treats under-18s who are unsure about their gender identity.

In a letter responding to Cass’s report, which NHS England sent on Tuesday to the seven trusts that host adult gender dysphoria clinics (GDCs), it told them: “We will be launching a review into the operation and delivery of the adult GDCs, alongside the planned review of the adult gender dysphoria service specification.”

NHS sources said that the review would be comparable to Cass’s inquiry. It was prompted by a lack of reliable evidence on key issues involved in the care of children and young people who are questioning their gender identity, such as the safety and efficacy of puberty blockers and cross-sex – masculinising or feminising – hormones.

“It will be external, rather than done in-house. It will be led by someone external. It will be fairly similar to what Cass did with children’s services, but this time it will be looking at adult services”, a source said. It could “conceivably” be a senior doctor like Cass.

The new initiative is reportedly being launched because of “an increasing incidence of individuals seeking to ‘detransition’ following previous gender-affirming interventions and the absence of a consistent defined clinical approach for them,” according to NHS England’s National Director John Stewart and Professor James Palmer, medical director of specialized commissioning.

The announcement appears to have received mixed reactions. A charity aimed at supporting transgender individuals acknowledged that Cass’ report “recognizes the current system is failing trans youth” but expressed concern “that some of the language in the report is open to misinterpretation and could be used to justify additional barriers to accessing care for some trans young people in the same way the interim report has been."

There are some indications that there could be more resistance to the initiative to focus on transgender adults. During Cass’ inquiry, six clinics refused to cooperate despite being contractually required to do so.

Cass said there was “no substantive reason” for their refusal, which seems to indicate a political or ideological motive in their effort to conceal their practices.

It is expected that this initiative would elicit pushback from those who support the “gender-affirming care” model. Proponents argue that it is the only way to ensure that those who are confused about their gender will not continue to suffer. However, Cass’ study showed that there is a serious dearth of evidence supporting the notion that prescribing puberty blockers, hormones, and surgical treatments for minor children was beneficial.

Indeed, other studies have indicated that these practices only cause more harm in a significant percentage of children who are subjected to them.

Cass’ inquiry resulted in the NHS announcing that it would no longer push these treatments for kids except in clinical trials.

The policy change is rooted in concerns over the lack of long-term evidence that “gender-affirming care” treatments are safe and effective for minors. The decision represents a significant moment in the ongoing debate over how to treat children who are confused about their gender.

England's National Health Service banned the use of puberty blockers for children seeking treatment for gender dysphoria, citing limited research.

Puberty blockers, or gonadotropin-releasing hormone analogues (GnRHa), is a class of drugs that suppresses sex hormones in adolescents by continually stimulating the pituitary gland. It will now only be available to children in limited ways, such as clinical trials.

The NHS's website said, "Puberty blockers (gonadotrophin-releasing hormone analogues) are not available to children and young people for gender incongruence or gender dysphoria because there is not enough evidence of safety and clinical effectiveness."

NHS England had previously ordered the London-based gender identity clinic at the Tavistock and Portman Trust to shut its doors amid safety concerns.

The new inquiry will certainly run into some obstacles. There are still many who believe that pushing these treatments is the most effective way to address mental health problems in those identifying as transgender. Still, the study could produce some interesting results that fly in the face of those supporting “gender-affirming care,” which is likely the primary impetus behind the resistance to the inquiry.