JR Rowling waded into a Labour row over puberty blockers for children today as she defended the new Health Secretary’s decision to keep a Tory ban on their use.

The Harry Potter author and gender rights campaigner backed Wes Streeting as he  faced a backlash from backbenchers and activists over a decision to keep the prohibition on the strong drugs.

Mr Streeting spoke out yesterday to defend his actions, saying he was ‘treading cautiously’ because the long-term impact on young people taking the drugs is unclear.

In a social media thread he warned: ‘We don’t yet know the risks of stopping pubertal hormones at this critical life stage.

He also hit out at ‘highly irresponsible’ statements by critics, after barrister Jolyon Maugham claimed his decision to keep the restrictions in place would ‘kill trans children’.

In the wake of his defence Harry Potter author Ms Rowling, a gender rights campaigner, wrote: ‘It is a mark of how febrile and often vicious the discourse around child transition has become that this humane, considered thread from Wes Streeting comes as such a relief.’

And later she posted a video of Culture Secretary Lisa nandy defending his stance, with the comment: ‘The times they are a-changin’.

The Harry Potter author and gender rights campaigner backed Wes Streeting as he faced a backlash from backbenchers and activists over a decision to keep

It emerged on Friday that Mr Streeting wants to make permanent the emergency ban on private prescriptions of puberty blockers for gender-questioning children which was brought in by the Conservatives in May.

The NHS had already ended routine use of the drugs after the landmark Cass review questioned the evidence behind gender medicine.

Defending his position Mr Streeting said: ‘(The) Cass Review found there is not enough evidence about the long-term impact of puberty blockers for gender incongruence to know whether they are safe or not, nor which children might benefit from them.

‘The evidence should have been established before they were ever prescribed.

‘The NHS took the decision to stop the routine use of puberty blockers for gender incongruence/dysphoria in children.

‘They are establishing a clinical trial with NIHR (National Institute for Health and Care Research) to ensure the effects of puberty blockers can be safely monitored and provide the evidence we need.’

Mr Streeting said clinicians can prescribe blockers to children who begin puberty too early because this has been ‘extensively tested’, and added: ‘This is different to stopping the normal surge of hormones that occur in puberty. This affects children’s psychological and brain development.

‘We don’t yet know the risks of stopping pubertal hormones at this critical life stage.

‘That is the basis upon which I am making decisions.

‘I am treading cautiously in this area because the safety of children must come first.’

Good Law Project director Mr Maugham, notorious for clubbing a fox to death with a baseball bat while wearing a kimono, is challenging the ban in the High Court.

He wrote online: ‘My feelings about Wes Streeting are unprintable. These measures will kill trans children.’ Since then at least four Labour MPs have tweeted in support of trans healthcare and against the ban.

This is an early sign of the pressure the new government will face from its own side over the contentious issue.

They included Stella Creasy who wrote: ‘Cass review recommended caution, not exclusion, for any treatment and drew attention to shortcomings of previous service.

‘To those asking [I] will always be MP who listens to demand for better research & evidence base for help for those with gender dysphoria, not abandons them.’

Zarah Sultana said: ‘Labour’s manifesto promised to ‘remove indignities for trans people who deserve recognition & acceptance’. That entails ending the Tories’ ban on puberty blockers.

‘Young people – cis & trans – must have access to healthcare they need. I’ll always stand with the trans community.’

Nadia Whittome wrote: ‘Only a small number of young people are prescribed puberty blockers. Those who are often describe them as life-saving.

‘I know the distress the puberty blockers ban is causing them. No matter what happens in court, I will continue fighting for the Government to scrap it.’

Apsana Begum said: ‘Trans people need to be able to exist safely as themselves with respect & dignity, and with equal access to adequately funded healthcare.

‘I stand in solidarity with the trans community – including young trans people – for whom puberty blockers are a life-saving me