As IT is the must-have toy of the moment, Lorraine Hardy was happy to indulge her eight-year-old daughter Isabella’s pleas for more L.O.L Surprise! dolls to add to her collection.

For anyone who has yet to encounter the phenomenon, these are the tiny dolls — just a few inches tall — that have become one of Britain’s best-selling toys, thanks to their huge doe eyes and candy-coloured outfits.

The tiny dolls have become one of Britain’s best- selling toys

But it wasn’t just the appearance that had kept Isabella, eight, hooked since the age of four.

Every time she got one for Christmas or a birthday, she loved the suspense of unwrapping the seven crinkly plastic layers of spherical packaging it came in — each yielding a new surprise, often accessories like tiny shoes or a new dress for the doll within.

Yet now it seems that each time Lorraine, a former social work manager with 20 years’ experience in child protection, shelled out around £10, she may have been in for even more of a surprise than she had bargained for.

Lorraine, 40, of Chalfont St Peter, Bucks, says: ‘When I saw the reports on social media that some of them had hidden underwear if they were put in cold water, I decided to give it a try.

‘Frankly, I thought it was a hoax, because I found it hard to believe that one of the world’s biggest toy companies would do something like this.

‘Why would a doll that was meant to represent a toddler — some have dummies in their mouths — be secretly dressed in an outfit that looked more suitable for an adult to wear to an S&M club?’

As Lorraine immersed four of Isabella’s dolls in the bowl, with her bewildered child looking on, she found that, within seconds, two emerged with adult-style underwear. When she checked all of her daughter’s collection of 20 dolls, half had similar undergarments when they are put in water.

Parents say that the tiny dolls reveal adult-style lingerie when plunged in water

‘These were not proper vests, pants or swimwear,’ says Lorraine. ‘Some of it was cross-over bondage-style stuff, accessorised with a mask.

‘I was horrified that I’d given hundreds of pounds to a company encouraging the sexualisation of children. I felt duped.’

Looking at the outraged posts on social media and numerous clips of other mums also revealing the dolls’ hidden underwear in water, so, it seems, do many other parents, with some reporting they have discovered devil’s tails, tattoos and fishnet stockings on the toys when they wet them.

They are also angered that, although the packaging said that some dolls change colour when wetted, there was no warning that such a change would reveal sexualised undergarments

In response, the company behind L.O.L Surprise! dolls, MGA Entertainment, issued a statement saying it has implemented ‘corrective measures to our design’ after admitting ‘a small number showed inappropriate attire or markings’.

However, this was not before MGA made a vast fortune out of its best-selling product line which it launched in 2016.

Last year alone the LA-based firm is estimated to have netted $5 billion (£3.9 billion) from sales of the dolls that are available from retailers including Argos and John Lewis, and outsell Pokemon, Barbie and even Star Wars toys.

But perhaps the man behind L.O.L Surprise! dolls, Isaac Larian, the billionaire head of the privately-run family company, should not be surprised by the furore. After all, he knows how well sexualised dolls sell to little girls. This is because in 2001 the 66-year-old grandfather was the man who brought Bratz to the market. These hyper-sexualised dolls with their inflated pouts and ‘hooker-chic’ wardrobes sold in their millions but were also widely criticised.

Their appeal spread so fast that the American Psychological Association issued a report saying: ‘It is worrisome when dolls designed specifically for four- to eight-year-olds are associated with an objectified adult sexuality.’

Parents argue that lthough the packaging said that some dolls change colour when wetted, there was no warning that such a change would reveal sexualised underwear

Last year, Larian defended the decision to add genitalia to boy L.O.L Surprise! dolls, even though no warning was given to parents.

There has also been controversy about his company’s Na! Na! Na! Surprise dolls. Last month, Tesco was among the retailers who removed the products from sale after Adam Weaver, 35, from the Vale of Glamorgan, spotted one he had bought for his seven-year-old daughter Savannah came wearing a lacy pink corset — with a full set of stockings and suspenders.

He told the supermarket: ‘I’m a pretty chilled-out guy but I was shocked by it. It seemed more of an adult-style doll than something for young girls.’

Last month, toy giant Hasbro pulled a Poppy troll doll from the shelves after a petition signed by 300,000 people accused the toymaker of promoting child abuse —by placing a button between her legs which made her giggle.

The firm has since withdrawn them from sale, saying ‘this feature was designed to react when the doll was seated but we recognise the placement of the sensor may be perceived as inappropriate.’

So do we really need to be worried about the insidious sexualisation of toys for young children? Aren’t they just pretty pieces of plastic?

When I wrote my book Girls Uninterrupted, I found there was unanimous agreement among parents that it was not a good idea to dress four-year-olds in hotpants, high heels and boob tubes.

Yet, at the same time, some mothers continued to defend their right to give their daughters dolls dressed in exactly this way.

Talking about the L.O.L Surprise! dolls, one mother commented on Mumsnet: ‘My daughter doesn’t see fishnet tights. She sees a pattern on their legs. She doesn’t see raunchy underwear — she sees swimwear. She’s never been exposed to those other things, so she would never think that way.’

However, child psychologist Emma Citron believes we ignore the return of creeping sexualisation of toys at our peril.

‘The L.O.L Surprise! doll is a sort of sexually sinister version of the old Kinder egg that kids used to unwrap to get to the prize inside,’ she says. ‘What’s particularly insidious about this is that the parents don’t necessarily realise when they’re buying.

‘These dolls reinforce all the negative stereotypes about women and girls and what their bodies are for, that is, that they’re about titillating others.’

Studies have shown what happens when children are given sexualised dolls to play with. Even when quizzed about more demure predecessors, one study published in the journal Sex Roles in 2014 found that girls who play with Barbies — the first doll to cause controversy for her unrealistic body shape — believed they had fewer career options.

In one study, 37 young girls between the ages of four and seven were randomly asked to play with either a fashion Barbie, a career-driven doctor Barbie or a ‘more neutral’ Mrs Potato Head for ten minutes.

The youngsters who played with a Barbie doll saw themselves as able to do fewer occupations than boys, whether they had played with the doctor or fashionista version, while the ones who played with Mrs Potato Head felt they could try just as many.

In another study, published in the same journal, researchers used different dolls to discover that girls as young as six are already starting to think of themselves as sex objects. Sixty children, aged six to nine, were shown two dolls, one dressed in tight and revealing ‘sexy’ clothes, and the other wearing a fashionable but covered-up loose outfit.

Questions asked by researchers included asking each girl to choose the doll that looked how she wanted to look, or looked like she would be the popular girl in school. Seven out of ten said the sexy doll looked how she wanted to look, and assumed she was more popular than the non-sexy doll.

Lead researcher Christy Starrs said: ‘It’s very possible that girls wanted to look like the sexy doll because they believe sexiness leads to popularity, which comes with many social advantages.’

Girls’ beliefs that they have to be sexy or look more grown-up to be popular with their peers is also exploited by L.O.L Surprise! dolls

Last year, the man behind  L.O.L Surprise! dolls, defended the decision to add genitalia to boy dolls, even though no warning was given to parents

In one of the brand’s music videos, seen by 187,000 viewers on YouTube, two ordinary teen school girls are seen being looked down on by more fashionable, sexy peers. That’s until the cartoon L.O.L Surprise! dolls — with miniskirts, make-up, jewellery and high heels — swoop in to give them a make-over and dress them the same way.

When the girls return to their real lives, they miraculously find themselves being noticed and accepted. It’s a depressing message to send to young girls. Give them dolls representing their own childlike bodies but dress them in clothes for grown women and it’s no wonder they are confused.

They are being co-opted into an adult world, often in clothing fashioned by grown-up sexual tastes, which in turn are being moulded by the availability of more extreme pornography. Because our young daughters don’t know anything different, they assume it’s what grown-ups expect of them.

Hyper-sexualised dolls send the message they should look hot, too. Not later. But now.

According to a report by the American Psychological Association: ‘One particularly pernicious effect of the constant exposure to sexualised images of girls is that individuals and society may be “trained” to perceive and label sexualised girls as “seductive”.

‘Images of precocious sexuality in girls may serve to normalise abusive practices such as child abuse, child prostitution and the sexual trafficking of children.’

Even if the dolls were not dressed as they are, L.O.L Surprise! dolls seem cynically designed to cash in on children’s development in other ways. When he dreamt up the idea, Larian says he latched on to the idea of unboxing — a YouTube craze in which children are filmed simply opening up boxes of new gadgets and toys — and which regularly attract millions of views.

Before they open the wrapping, girls don’t know which doll from the series they are going to be able to add to their collection. Once inside, however, they get a leaflet showing the full range of up to 45 others they can get next.

Lorraine checked her daughter’s collection and found that all 20 dolls revealed secret lingerie

Children get hooked on the dopamine hit of the anticipation and expectation of what’s inside.

Dr Richard Freed, a child and adolescent psychologist and author of Wired Child: Reclaiming Childhood In A Digital Age, says: ‘The unboxing trend capitalises on the anticipation humans have when they want something. It’s not as much about the reward as it is the excitement of the reward that can trigger the dopamine.’

Beyond that, if you want any more proof of how sexualised dolls influence children then look at the first generation of young women to grow up with Bratz.

Take a tour of YouTube and you will find hundreds of clips of young people — often with the same overinflated lips and plasticised complexions —giving Bratz make-up tutorials to complete the look. In one episode of the soon-to-be-defunct Keeping Up With The Kardashians, Kendall Jenner asks her younger sister Kylie: ‘Does anyone ever tell you you look like a Bratz doll?’

For Lorraine Hardy, finding out how surprising L.O.L Surprise! dolls are has made her determined her own values won’t be drowned out by the commercial ambitions of global toy companies.

‘I’ve explained it all to Isabella, who doesn’t want to play with them any more — but why should I have to explain to my eight-year-old why her dolls are dressed in fetish gear? I have been put in a position where I have unknowingly supported the sexualisation of children, something I have fought against throughout my career.

‘I’m really wondering what sort of world we live in when, instead of caring about children, a major toy company uses them as collateral damage in their drive for profits.’

Tanith Carey is the author of ‘Girls Uninterrupted: Steps For Building Stronger Girls In A Challenging World and What’s My Child Thinking? Practical Child Psychology For Modern Parents.