Dressed in a smart blue polo shirt and jeans, he looks and acts much like any other six-year-old boy. Nobody would suspect that Dexter, aged 6, was actually born a girl

Dexter Jones stands 4 ft 1 in tall, lithe and skinny as a whippet, with a mischievous smile and an appetite seemingly unsated by the entire punnet of blackberries he has just polished off.

He adores Harry Potter — he knows all the wizards and spells — and would love to run in the Olympics one day. Dressed in a smart blue polo shirt and jeans, he looks and acts much like any other six-year-old boy. Nobody would suspect that Dexter was actually born a girl.

Three years ago — without prompting from his mother, Mienna says — pretty, tomboyish Talia announced that she was a boy. Not that she wanted to be one, but that she actually was one. Now. And always had been.

Mienna, a 44-year-old childminder from St Albans, Hertfordshire, wasn’t shocked. Talia, she says, then three, had railed against her assigned gender since she was a toddler, shunning dresses and dolls and behaving entirely like a little boy. Talia was just being Talia, she thought, and she’d grow out of it. Her elder daughter had played with cars for a while, after all.

By age five, however, Talia was gone. She declared one day that she was actually a boy called Dexter — a name she admired from a boy at school — and that this was who she was going to be from now on.

Backed by his family, teachers and GP, Dexter was referred to the Tavistock Centre in London, an NHS clinic for transgender children, and became one of its youngest patients.

Mienna was eventually told that Dexter had gender dysphoria — a condition where sufferers experience distress at their sex. Should he still feel this way as he approached puberty, he could be given drugs to block the changes and ease the transition to becoming a man in adulthood.

This would, undoubtedly, be a long, and possibly painful, journey — and it is starting strikingly early.

Many will be disturbed at what is happening to this child. Isn’t Dexter far too young to be questioning his gender, let alone taking preliminary steps to alter it?

How can Mienna be sure, at such a tender age, that this isn’t just a phase the child is going through? And doesn’t she worry that psychological harm could be inflicted on the child by validating what could be temporary as a biological certainty?

Many will be disturbed at what is happening to this child. Isn’t Dexter far too young to be questioning his gender, let alone taking preliminary steps to alter it? Pictured: A girl at 18 months

She admits she can’t be sure. ‘But, for me, it would be fundamentally wrong to force Dexter to live as Talia, because he was so unhappy,’ says Mienna, who is married to Ollie, 54, a painter, and who also has a 13-year-old daughter. ‘We’re a long way off any treatment or an operation, but being under the umbrella of the Tavistock makes us feel that we’re in safe hands.

‘As horrible a road as this is, I am thankful that we are dealing with it now. It must be an absolute torment to discover you are transgender during the tricky teenage years.’

The subject of gender identity in childhood has become one of the most contentious of our times.

Last week, Nigel Rowe, 44, and his wife Sally, 42, announced plans to sue their sons’ Church of England school on the Isle of Wight for discriminating against their Christian beliefs by allowing boys to wear dresses.

They said it was deeply unsettling for their sons to see other children affecting a different gender, and that children are too emotionally immature to decide they want to change sex. In an age where gender is increasingly seen as fluid, the Rowes were vilified for their beliefs. Unsurprisingly, Mienna is angered.

‘If the Rowes are acting in the name of religion, surely they should be more accepting of others? My son has shown more emotional maturity than they have.’

The number of children seeking help for gender issues has grown dramatically recently, despite — or perhaps because of — increasing attempts to identify and integrate those who might be transgender. Demand at the Tavistock Centre, the only NHS clinic of its kind, has soared in recent years. In 2009, just 97 children aged between three and 18 were referred. But by last year, there were 2,016 referrals, with the number of children aged five or under rising from six to 32.

Meanwhile, the gender-neutral movement gathers pace. Earlier this month, John Lewis stopped labelling its children’s clothing by gender, while Priory School in Lewes, East Sussex, banned girls from wearing skirts in order to accommodate the growing number of transgender pupils.

This week, The Good Schools Guide is to examine the extent to which schools are ‘transgender friendly’, after claims some children are being bullied.

Yet others believe, like the Rowes, that there is a politically correct agenda driving the issue in schools, and that transgenderism has morphed from a serious condition affecting a small minority to a fashionable ideology spearheaded by fanatics who bully those who don’t subscribe to it.

A friend questioned whether Dexter may be transgender — a suggestion Mienna promptly rejected. Pictured aged 3

Mienna says she certainly had no plans to raise her children gender-neutral, but by the age of two, Talia was throwing tantrums at the sight of frocks and frilly necklines and would drag her mother to the dinosaur T-shirts in shops.

‘She hated the cartoon princess film Frozen and watched ET instead,’ says Mienna. ‘Nearly all her friends were boys and she didn’t seem to identify with girls. When I praised her for being a “good girl”, she’d protest: “I’m not a girl, I’m a boy.” ’

A friend questioned whether Dexter may be transgender — a suggestion Mienna promptly rejected.

‘I was a tomboy and thought she was, too,’ she says. ‘Of course, I’d heard of transgenderism on social media and television, but I’d never met a transgender child — neither had Talia — and it never crossed my mind.’

But Talia seemed more and more unhappy. ‘She was a poor sleeper and cried constantly. I’d assumed she was just spirited, but as she approached her fourth birthday, I wondered if there might be some truth in the transgender suggestion.

‘She was so persistent in her language and behaviour.’

She says her husband Ollie has been ‘100 per cent supportive’ of her approach towards Dexter: ‘Like me, he watched the situation evolve.’

When visiting Talia’s prospective primary school in 2015, Mienna asked the headmaster if Talia would be able to come to school in a boy’s uniform. ‘He said she could wear what she was most comfortable in,’ says Mienna.

Yet Talia struggled. ‘She was wetting herself and eventually told me the girls wouldn’t let her use their toilet as she was a boy, and the boys wouldn’t let her use their toilet because she was a girl — so she wasn’t going at all.’

'Weight off his shoulders': Dexter is much happier now than when he was a girl

A month into the term, Mienna gave in to Talia’s pleas to have her long, curly hair cut short. Then, one afternoon in March, Talia, aged five, came running in from the garden with an announcement.

‘She said: “Mummy, I’ve got it — I’m a boy called Dexter and I want everyone to call me that”,’ says Mienna.

‘Later, I asked if she was sure, and she said: “Yes, I’m a boy.” It seemed as if a weight had been lifted off her shoulders.’

Mienna met with Dexter’s headmaster, teacher and an ‘inclusion officer’ — who helps children with special needs — to say that, from the summer term, Talia wanted to be known as Dexter and addressed by the pronoun ‘he’.

‘Dexter’s teacher told the rest of the class Talia was to be called Dexter while Dexter and I were in a meeting. Apparently, one of Dexter’s friends said: “We know Tali’s a boy. Can we play now?” ’

Mienna disputes the Rowes’ implication that Dexter’s classmates could be damaged by his behaviour.

‘Yes, children are inquisitive, but they also take things at face value,’ she says. ‘If that child is their friend, why would it make a difference?’

And she doesn’t worry that seeing Dexter’s changes might encourage children to needlessly question their own gender.

‘This isn’t something you question,’ she says. ‘It is something you feel. Dexter has never said he wants to be a boy. He says he is a boy. It’s different from being gender-fluid, going through a phase or being a tomboy.’

Mienna also dismisses the claim made by author and academic Dr Joanna Williams that ‘the time, effort and money that goes into producing and monitoring transgender policies is out of all proportion to the tiny number of trans children currently in British schools’ as deeply unfair.

She says: ‘If there was only one child in a wheelchair or with autism, nobody would say they didn’t deserve as much time and effort. Dexter’s needs are just as valid.’

In any case, she adds: ‘The other parents were incredibly supportive. Only a couple of people asked something to the effect of whether this was my decision because I wanted a boy.

‘I couldn’t believe they thought I would push this onto my son, or saw fit to say so.’

Mienna’s father, 74, and mother, 65, who live nearby, have been similarly understanding. ‘I worried my dad wouldn’t get it,’ says Mienna. ‘But my mum sat him down and explained everything. Since then, he hasn’t once slipped up and called him Talia.’

Dexter’s teacher, meanwhile, suggested Mienna and her son watch some TV programmes about transgender children. The more Dexter watched, the more questions he had. Mienna says: ‘He asked me why I made him wrong. I explained to him what transgender meant and said there was an operation you could have to make a willy. I told him if he still feels this way when he’s an adult, he may or may not choose to have this operation.

‘He started asking: “When am I going to get a willy, Mummy?” I’d never suggested he was broken or needed repairing. But it was heart-breaking, and I felt guilty.’

Does she fear that exposing him to such complex issues on-screen might have made him feel more unsettled?

‘No. It’s not as if he is this way because I watched all this with him. I wanted to be honest.’

But Dexter continued to struggle to sleep and, when he started complaining of stomach aches in May 2016, Mienna took him to their GP, worried that he was suffering from anxiety.

After a week of research, the GP referred him to the Tavistock Centre, where Dexter attended his first appointment in January with his sister and parents.

‘Dexter asked if they were going to “fix” him,’ says Mienna. ‘I had to do all the talking, going back over his upbringing. He coloured in as I talked, and there was no definitive answer as to whether he was transgender.’

The family have now had three of their allocated six NHS-funded counselling sessions at the Tavistock, with the next in November. ‘As Dexter isn’t about to hit puberty, we have a while before we need to go more regularly,’ says Mienna. ‘They told us gender is very fluid at Dexter’s age and some children do revert back.’

Can she see this happening? ‘Never. I’d gladly be proved wrong — it would be far easier if Dexter did decide to be a girl. But there has been no suggestion he will.’

She seems in favour of him taking drugs to stop the onset of puberty. ‘I can imagine it would be horrific to grow breasts and get periods if he feels the way he does now.’

In the past, it has been more common for boys to seek treatment than girls, but there has been a marked reversal recently, with 1,400 females doing so last year, compared with 616 males.

Some have ascribed this rise to the growing pressure girls are under, but Mienna says: ‘It’s never crossed Dexter’s mind that life will be easier as a boy. Nor is this about feminism or being gay.’

In fact, she says, Dexter talks of having a wife and children when he is grown up. ‘He’ll probably have to adopt, unless he doesn’t transition and lives as a man with female organs,’ says Mienna.

While she admits that Dexter still ‘struggles’ to fit into his peer group, she says he is not lacking in playdates and party invitations.

‘Like any mum, I just want my child to be happy,’ she says. ‘And really, as long as he is comfortable in what he’s wearing, I can’t see what difference it makes to anyone else.’