Sharon Hall is a small, timid figure with wide brown eyes that dart nervously between the floor and her hands as she speaks.

During our conversation, her sentences fluctuate between slow, fractured prose and sudden, spluttering outbursts as her words fall over each other in a fight to assemble. It has been almost 10 years since Sharon last tried to speak about the childhood memories she has spent much of her life trying to suppress – and that particular encounter, as we shall see, left her feeling sorrily dejected. The experience of sharing her story today she describes as a gruelling rite of passage, one she feared would prove too painful to complete: "Every moment I feel the effects of what I went through," she starts in a small, raspy voice, pausing briefly to brush an imaginary strand of hair from her cheek, before continuing, "I've been trapped by my past for all these years. Being able to finally talk about it is strangely exhilarating."

The story that Sharon, who is now 40, has been unable to tell before today is one that few would wish to hear: from as far back as she can remember until the day she left home at the age of 16, Sharon, an only child, was sexually abused by her mother. The particulars of her abuse are too horrific to bear repeating in detail; this was sustained sexual violence, which she suffered silently at the hands of the one person who was supposed to love and protect her above all others.

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Sharon's ordeal went undetected for her entire childhood, despite her becoming increasingly withdrawn over the years; her weight fell to below six stone by the age of 15, and she had few if any friends at school. The problem was, she says, that even if others had suspected something was wrong, few would have guessed what it was – and fewer still would have wanted to know the whole truth. "I did try telling my doctor once," she says, blinking heavily, pulling at her shirt, "but it's like I said, no one really wants to know that."

It was at the age of 30, when she became pregnant with her own daughter, that Sharon finally summoned the courage to speak to her GP for the first time about what had happened to her. Her fear was that if she didn't seek help to overcome her issues, they could in turn have a damaging effect on her unborn child. But her doctor's response was: "Don't be silly, mothers don't sexually abuse children. You're understandably worried about becoming a parent yourself, but don't let your imagination run away with you."

And it seems this reaction is all too common.

While researching this piece, I spoke to a number of adults – men and women – who as children endured horrific sexual abuse at the hands of their mothers, aunts, grandmothers and female carers. Very few of them had ever had a chance to tell their story before, and the effect of keeping their experiences to themselves for so long has had a disastrous effect on their mental state.

Sharon's mental scars are manifest in her serious anorexia and agoraphobia, and the effect on her daughter has been devastating, too; Debbie, who is now 10, suffers from severe panic attacks and low self- esteem. "The problem," Sharon explains, "was that I never knew how to bond with Debbie. I was terrified of even touching her."

Sharon says that she might have learnt to cope better if she had been given the help she so desperately needed when she approached her doctor before her child was born. "You can't imagine how deflating it is after all those years of keeping your disgusting secret to finally get the courage to tell someone and then be told that you're making it up," she recalls. "But the worst thing about it is that even though my mother is now dead – and never even met her granddaughter – she has managed to ruin my daughter's childhood too."

The systemic denial of female sexual abuse is one of the scandals of our times. While in recent years the issue of male paedophilia has been placed firmly at the forefront of public debate in Britain, with endless high-profile media and Government campaigns bringing this formerly underground issue into the public spotlight, it seems that the involvement of women in cases of child molestation is an enduring taboo, and in order to break that wall of silence we must start by addressing a series of serious shortfalls that run throughout the child protection services in this country.

According to Zoe Hilton, policy advisor for child protection at the National Society for the Prevention of Cruelty to Children (NSPCC), "Professionals in all areas of the system tend to be disbelieving of cases of female sexual abuse". In her role at the NSPCC, Hilton is responsible for lobbying the Government and advising on what systems need to be put in place to tackle the sexual abuse of children across the board. She argues that – as a first step – there needs to be "far more training and education and greater reporting of female sexual abuse when such cases do come to light".

Yet, she continues, it is hard to imagine how the child welfare system is supposed to progress when the underlying denial of the issue of women who sexually abuse runs far deeper, throughout society and into the very Government departments charged with overseeing and directing these individual welfare organisations.

Hilton is not the only one to have noticed how deep-rooted the problem is. Michele Elliott is the founder of the children's charity Kidscape, which she set up in 1984. She observes that the situation now is very similar in many respects to that in the Seventies and Eighties, when the existence of paedophilia in any shape or form was scarcely believed. Around the time that she set up Kidscape, Elliott recalls approaching the Department of Health and expressing concerns over the cases of male sexual abuse she was learning of in her line of work. The response of officials there, she says, was: "This is not a problem in this country."

These days, of course, we can hardly ignore the issue of the sexual abuse of children in Britain. According to ChildLine, the 24-hour counselling service provided by the NSPCC, the number of reports they receive is at an all-time high. Some 13,237 children called their helpline with such stories – an increase of more than 50 per cent in three years. The NSPCC claims that as many as one in six people in Britain suffers sexual abuse by the time they are 18 years old. Yet, while such figures have forced us to face the reality of male child sex abuse in the UK, there are enduring myths that surround our ideas of paedophilia – including ideas about the type of people who abuse.

As well as founding Kidscape, Elliott is also a child psychologist with 40 years' experience and the author of Female Sexual Abuse of Children: The Ultimate Taboo. She understands all too well that predators come in all shapes and sizes, male and female. In the early Nineties, while researching her book on female sexual abuse, Elliott was a guest on the Richard and Judy breakfast show. During her brief television appearance, she invited viewers with personal experiences of female sexual abuse to phone in and share their stories. Immediately, she says, the lines started buzzing. There was barely enough time on air to answer a fraction of the calls she received from men and women of all ages, from across the country, getting in touch to share their stories.

Since then, Elliott has been contacted by some 800 victims, 780 of them in the UK, each desperate just to talk. In a large percentage of these cases, the abuse took place within the family home, which is one of the reasons why cases of female sexual abuse are so incredibly hard to spot. Yet, sadly, this doesn't mean that the abuse isn't happening. As Elliott points out: "Considering that I am just one woman working for one relatively small charity, and this many people have managed to get in touch with me, I dread to think of the true scale of the problem."

Extraordinarily, in the vast majority of cases involving female sexual abuse (of both boys and girls), the child's mother turns out to be involved in that abuse, whether offending alone or with another woman or a man. Almost all of the victims who have contacted Elliott to share their stories have mentioned being "brainwashed", and many have spoken of being made to believe that their abuse was what constituted parental love.

Very few have ever before felt able to talk about the abuse because they feared they would not be believed – and those who have already come forward, to a doctor or therapist, have usually had their worst fears realised. One man, now 60 years old, recalls: "When I tried to tell my therapist of my abuse when I was 35, I was told: 'You are having fantasies about your mother and you need more therapy to deal with that.' In reality, my mother had been physically and sexually abusing me for as long as I can remember. The abuse was horrific, including beatings and sadomasochistic sex."

Another victim recalls how she had been sexually abused by her babysitter between the ages of six and 10. She explains: "I actually thought all babysitters did that to kids until we got another babysitter. When I tried to get her to have oral sex with me she told my mother and I got into trouble. Believe me, from then on I kept it a secret."

Quite how much it meant just to be listened to and believed was summed up in one letter sent to Elliott soon after her appearance on Richard and Judy: "Finally someone is willing to open up the subject of female sex abuse and really listen to us victims," the woman wrote. "This is fabulous – a day I never thought would come." But sadly it seems her response might have been optimistic, as very little seems to have been done on a wider level in the intervening years to help bring the matter of female sexual abuse out into the open.

And this view is one corroborated by a number of frustrated officials currently working in child welfare organisations and different parts of the British justice system, who wish to remain anonymous. These individuals say they just aren't being given the tools they need to address this issue, or even being made aware that it is an issue at all. This is perhaps not surprising when you learn that there is hardly any official information available pertaining specifically to the area of women who sexually abuse children, and barely any research being carried out, either. There have been a couple of Government-led initiatives to educate officials in welfare agencies about the issue – including a conference held in Manchester last April entitled "Child Abuse: The Female Offender". But still nowhere near enough is being done.

In fact, during the course of my research for this article, all I could find – under the direction of several Government press officers, from the Ministry of Justice to the Home Office – was a figure relating to the number of women who have been convicted of sexual offences in the UK. This figure derives from a report released in 2006, and suggests that women form just 0.5 per cent of all sex offenders in prison, and around 1 per cent of convicted sex offenders in England and Wales.

Yet this is not entirely helpful – as conviction rates in cases involving sexual offences across the board are hardly indicative of the true state of affairs. Indeed, the 0.5 per cent statistic might be more useful in highlighting the shortcomings of the British justice system than painting a true picture of female sexual abuse. Prosecutions in cases of sexually motivated crimes in the UK are generally few and far between, and rarely reflect the true story. Take the proportion of reports of rape cases that result in prosecution in Britain, for instance. This is the lowest in Europe, according to a study released earlier this year, which claimed that the rate in England and Wales is just 6.5 per cent, and an even more pitiful 2.9 per cent in Scotland.

Furthermore, conviction rates only tell us about cases that actually make it to court, and according to one expert, Hilary Aldridge, the large majority of all cases of sexual abuse aren't even reported – as many as 90 per cent, she says – let alone put before a judge. In the unlikely event that a case of sexual abuse is reported, there is still a long and arduous process to go through in order to get it to court.

Aldridge is the chief executive of the Lucy Faithfull foundation, one of the few organisations in the UK which works solely with female abusers. She works on a daily basis with offenders in cases referred to her organisation by the family and criminal courts. She explains how tricky it can be to get a case of child abuse to court. "In the first instance, a child has to first come forward and tell someone what is happening, which is often extremely difficult for them to do," she explains. "Or someone else needs to notice that something is wrong, and then pick up on what that is. They then have to make the police take the allegation seriously and if they are able to do that, which is often difficult, then the child protection services will become involved and someone there has to take it seriously, too."

All things considered, we might do better to look somewhere other than the Government data for an idea of the prevalence of cases of child abuse involving female offenders in the UK – and the most widely respected sources for this are the independent studies from ChildLine and the National Society for the Prevention of Cruelty to Children, which are believed to provide a much more accurate picture. Suddenly, the issue of female sexual abuse doesn't look quite as uncommon as we might otherwise have believed.

In 2004, childline asked each of those callers who were ringing their helpline about sexual abuse to tell them the gender of their abuser. It revealed that over the period of one year, 11 per cent of callers said they were being abused by a woman: a total of 8,637 children, of whom 6,538 were girls and 2,099 boys. The NSPCC also conducted its own research in 2005, the results of which suggest that around 5 per cent of children who suffer sexual abuse in Britain do so at the hands of a woman, which is the number regularly cited by other experts in the field. But as Zoe Hilton, the charity's policy advisor for child protection, suggests: "The true extent of female sexual abuse is still a hidden picture." Furthermore, it is not a picture that many seem in any hurry to clarify.

One of the biggest problems, of course, is that the idea that women can and do sexually abuse children is highly provocative in itself – a fact confirmed by a spokeswoman for the Child Exploitation and Online Protection Services (CEOP), a newly formed Government taskforce charged with "eradicating the sexual abuse of children" in Britain. "Women are perceived as the nurturers, those who are there to look after our young people," she explains, adding that female sexual abuse is often even more threatening than male sexual abuse as it undermines what we understand about the way women relate to children. In order for us to recognise it, the spokeswoman continues, we have to set our preconceptions aside. Otherwise, children will continue to suffer in silence: "How can a child be expected to understand they are being abused and that what they are enduring is wrong if we as a society cannot recognise women as abusers?" she asks.

Sexual abuse is usually understood as something bound up with issues of male aggression and power, and the idea of a female abuser totally undermines this well-established belief. Then there is a further problem in getting female abuse recognised: many people simply don't understand how – practically – a woman could abuse.

Understandably, this is a sensitive and highly emotive subject, the fallout from which Michele Elliott of Kidscape has witnessed at first hand. In 1992, she held a conference in London while compiling her book on the subject of female sexual abuse. She recalls how 30 women turned up to disrupt her address: "They stood up and started yelling about how terrible it was that I was detracting from the fact that male power was to blame. It is very disappointing when you encounter such extreme and closed-minded reactions. I was simply responding to what victims had told me."

And such closed-mindedness is rife in the criminal- justice system too, Hilary Aldridge confirms: "There is a tendency in the courts to see the woman as a victim of a male counterpart." But this isn't always the case by any means. Even when there is a male co-offender, this doesn't automatically mean that the female partner is an unwilling accomplice.

Indeed, one of the most disturbing aspects of child abuse committed by women is that – according to studies by independent researchers and highly respected charities – the large majority of it takes place in the home. Aldridge asserts that 60 per cent of cases take place within the family unit – and "women who abuse children regularly do so in the guise of normal, basic care". This, of course, is part of what makes it so hard to detect.

Sharon Hall, whose abuse by her mother went unnoticed for her entire childhood, knows all too well the devastating effects of being forced to suffer in silence. "If I'd had just the smallest impression that I'd be believed," she says, "I might have had the guts to come forward." The reality, she says, is that no one wanted to know what she was going through, and even today we continue to switch ourselves off from the suffering of an unknown number of children across the country.

If we are to have any chance at all of saving those children who are suffering now and those who will no doubt be suffering in the future, she says, the best place to start is by opening our eyes to the abuse going on around us. "I never had the chance to come to terms with what happened, and not only has my life been ruined, but so in turn has my daughter's," Sharon concludes. "All I hope now is that by coming forward and raising awareness of this issue, that I might in some small way be able to help those children for whom it isn't too late."

For confidential advice about female sexual abuse, call freephone 0808 1000900. Some names have been changed