A PSYCHIATRIC nurse is taking legal action to stop the NHS prescribing “experimental” puberty blockers and cross-sex hormones to children who wish to undergo gender reassignment.

Lawyers acting for Susan Evans will lodge papers at the High Court this week in the case against the Tavistock and Portman NHS Trust, which runs Britain’s only gender identity development service (GIDS).

Ms Evans was employed by the Tavistock as a psychiatric nurse but became increasingly concerned that young children were being given “experimental treatment” without adequate assessments.

She has also accused gender-diverse support groups of having undue influence on what happens at the clinic.

The case is also being brought on behalf of Mrs A, the mother of a 15-year-old autistic girl who is currently on the waiting list for treatment at the service.

Lawyers will argue that the provision of puberty blockers and cross-sex hormones at the clinic to under-18s is illegal as children cannot give valid consent to treatment.

Yesterday, in an interview with BBC Radio 4’s Today programme, Ms Evans said the Tavistock was willing to offer drugs to children under 16, and even as young as nine or 10.

She said: “I just couldn’t see that enough psychological work had been done with the children. They’ve lowered the age group for this experimental treatment.

“It’s an off-licence treatment, the drug was not developed for the purpose for which it’s being used.”

Ms Evans said the age limit has been lowered with children “perhaps” nine or 10 years old being asked to give informed consent to a “completely experimental treatment for which the long-term consequences are not known.”

She also warned that more than 30 per cent of children at the clinic are autistic, while “many have suffered some sort of trauma in their early lives” and others are confused and socially anxious.

“I think this rapid affirmation and fast-tracking after maybe four or five appointments needs to be questioned in the courts now,” she added.

A spokesman for the Tavistock and Portman NHS Foundation Trust said that GIDS is “one of the longest-established services of its type in the world with an international reputation for being cautious and considered.”

NHS England said it would not comment ahead of the hearing.