Smiling sweetly, with a floral headband keeping her shoulder-length hair in place, Zoey Middleton looks like any other schoolgirl.

But what may not be immediately obvious is that this 12-year-old from Derbyshire was actually born a male called Kian.

By the age of four, according to her mother Caren, she started wanting to wear girls’ clothes and began dressing up as ‘a bridesmaid’.

Zoey Middleton, aged 12, was born as male Kian, but enjoyed dressing up in female clothing from a young age

Then last year, just months after starting secondary school, Zoey told her parents that she wanted to live full-time as a girl and wear a skirt rather than trousers for school.

Now, in a move that will shock some parents, her mother and father are hoping that the NHS will put her on a course of powerful puberty-halting drugs that could change her life for ever.

In the next few weeks, they are hoping the Tavistock Gender Identity Development Clinic in London, which treats under-18s who believe they were born the wrong sex, will assess their daughter and begin this controversial treatment.

The monthly hormone injections will stop the onset of puberty, slowing the development of sex organs and body hair and delaying other changes, such as her voice breaking. The treatment is often the first stage towards a full sex change.

Earlier this year The Mail on Sunday revealed that 800 children in England – some as young as ten – are receiving the drugs, known as ‘puberty-blockers’.

But their use has sparked furious debate, with critics branding the NHS as ‘unethical’ for prescribing such life-changing drugs to young children.

Born Kian, Zoey is set to be assessed for gender reassignment treatment by a clinic in London

Some doctors are warning that the injections are still ‘experimental’ as little is known about their long-term effects. Others argue, however, that the treatment is essential to save transgender children from going through the agony of changing into the ‘wrong’ sex.

Caren, and Zoey’s father David, are aware of the wider controversy, but say their priority is their child’s happiness. And if this means taking injections to stop her turning into a young man, then that is what they think should happen.

Speaking at the family’s £200,000 three-bedroom home in Chesterfield, Caren, 44, said: ‘We do want Zoey to start the blockers because I think puberty will really affect her.

‘Her voice is quite girly at the moment. She likes her voice, she’s always singing and people think she’s a girl anyway. So it will seriously affect her if she hits puberty and things change. It’s a big worry. We’d like her to start the drugs as soon as possible.

‘She’s 12, but nearly turning 13, so it’s only a matter of time before she starts puberty. If taking the drugs is the way it’s got to be for her to be herself, then so be it. It’s not ideal, but her happiness is what matters.’

David has, by his own admission, wrestled with his child’s decision much more than her mother. ‘I struggled at first,’ the 47-year-old engineer confessed. ‘I was just worried about bullying at school. Schools are not always the nicest places. I tried to get her into football and dads’ and lads’ stuff but she’s never been interested.’

But now David says he is fully behind Zoey’s transition, including the prospect of her taking puberty-blockers.

Caren and David say they support Zoey and hope to begin hormone treatment for their child on the NHS

He said: ‘As long as she is happy that’s all I care about. If [taking the blockers] is what she wants, I’m 100 per cent behind her.’

After being assessed by psychologists at the Tavistock clinic, Zoey will be passed to the service’s medical department where she can then be prescribed the drugs.

For Caren and David it’s been a long and sometimes confusing experience. ‘When she was younger and role-playing, I always thought she’d grow out of it,’ Caren recalled. ‘But she was always so feminine and I thought, “She’s in the wrong body.” She always has been, really.

‘When she was four she started to want to dress up in girls’ clothes as if she was a bridesmaid. She wouldn’t want to wear boys’ clothes

‘She would watch a TV programme called Dinosaur King and started saying “Can you call me Zoey?” after one of the main characters.’ By the time she was aged nine, she was attending school discos wearing girls’ shorts, tights and plastic heels. She started wearing dresses at about the same time – but only in the house for fear of being teased if she went outside, Caren said.

The major turning point came during her first term at secondary school, when she asked her parents if she could wear a girls’ school uniform rather than a boys’ one.

Meetings followed with the headteacher, who not only let her come to school in her chosen uniform but also let her change her name from Kian to Zoey on the school register.

Zoey’s school already had gender-neutral toilets but it has allowed her to have a separate changing room so she doesn’t have to change with the boys or the girls for PE – a class she takes with the girls.

Zoey said she loves her new girls’ wardrobe, which is full of flowery dresses and bright-coloured leggings. She said: ‘I’m much happier and more confident now the way I am. And I just so happy that no one at school has ever been mean to me or asked me any funny questions.’

Her parents admit that seeing their child go to school dressed fully as a girl was difficult to get used to.

‘I wasn’t surprised, but I felt as if I was grieving because I’m losing a son,’ Caren said. ‘But as long as she’s happy, I love her whatever. I always encouraged her to be who she wanted to be, but in the back of my mind I always thought she would be older before she transitioned.’

Gender dysphoria is a complex issue and those diagnosed with it are often judged by the medical profession to be at higher risk of depression, self-harm and suicide.

In August this year, an inquest heard how 15-year-old Leo Etherington, who was born female, had hanged himself in his bedroom in High Wycombe, Buckinghamshire. The teenager had been the first young person to publicly reveal at the age of 12 that he had started receiving puberty blocking injections.

At the inquest his father told how Leo, who was previously called Louise, was ‘angry’ with his school after staff reportedly refused him permission to change his name until he was 16, though the school denied this. Last month in Australia, another teen named Patrick, who had begun taking puberty blockers, said he had ceased taking the drugs after changing his mind and deciding to remain male.

Previously, US psychiatry professor Paul McHugh has warned that prescribing puberty-blockers for young people with gender dysphoria is an ‘experimental’ treatment, unsupported by ‘rigorous scientific evidence’.

But Professor Gary Butler, from University College Hospital London, said the hormone injections ‘stop puberty going forward like a pause button.

‘They are designed to treat the very rare situation of a young child developing sexual changes. We think they are safe and reproductive changes reversible, but the drug can cause polycystic ovaries in women.’

However, for Zoey the process has gone well so far, and Caren says: ‘I don’t think she’ll ever go back to being Kian. She is so happy. Maybe I’ll be proven wrong in ten years’ time, but I would be very shocked.’

Society must 'back off' pushing sex change surgery for children, says Sir Salman Rushdie as he reveals concern over liberal attitudes to procedures

Satanic Verses author Sir Salman Rushdie says society needs to ‘back off’ promoting sex-change surgery to young people.

The 70-year-old writer says he ‘worries’ how children are being affected by more liberal attitudes to gender-reassignment procedures.

He adds: ‘I have quite strong views about the over-insistence on these issues, particularly when you get down to very young people.

Salman Rushdie has expressed concerns at how liberal attitudes to gender reassignment affect children

‘Because, to put it crudely, if there’s a boy who likes playing with dolls and wearing pink shirts it shouldn’t necessarily mean that he has to have gender-reassignment surgery.

‘Until quite recently that would never have occurred to anyone, so I think we maybe need to just back off a little bit.’

However, Rushdie insisted he did not want to be ‘stupidly judgmental’ about the issue, which he tackles in his new novel The Golden House.

He said: ‘My personal experience of people who have gone through this process as grown-ups is it’s been very beneficial to them, so I’m not hostile to it. But I’m just saying, particularly when it’s with little children, I worry about it.’

In an interview to promote the book, Mr Rushdie added: ‘There are two people I know quite closely who have transitioned – one in each direction – and in both cases these have been very successful. Both people seemed to me much happier now than they were before.’

The author famously spent more than a decade in hiding after a fatwa was issued by Iran’s Ayatollah Khomeini in 1989 following the publication of The Satanic Verses.

On the current climate of terror, he said: ‘The only answer is not to allow it to change us into being different kinds of people and not to allow our societies to become much more closed and repressive.

‘We have to have the courage of our convictions.’