In the midst of all the outrage about modern-day slavery, usually vulnerable men forced into manual labour, there is actually a far worse form of abuse going on in the UK. It happens in every city, town and even village. It’s endemic to every culture and region of the world, and yet these days we justify it in the name of ‘liberation’. We’ve become accustomed to thinking of prostitution as a legitimate way of earning a living, even ‘empowering’ for women. We call it ‘sex work’ and look away. We should not.

For the last three years I’ve been investigating prostitution worldwide to test the conventional wisdom of it being a career choice, as valid as any other. I conducted 250 interviews in 40 countries, interviewed 50 survivors of the sex trade, and almost all of them told me the same story: don’t believe the ‘happy hooker’ myth you see on TV. In almost every case it’s actually slavery. The women who work as prostitutes are in hock and in trouble. They’re in need of rescue just as much as any of the more fashionable victims of modern slavery.

One of the most disturbing discoveries I made was that the loudest voices calling for legalisation and normalisation of prostitution are the people who profit from it: pimps, punters and brothel owners. They have succeeded in speaking for the women under their control. The people who know the real story about the sex trade have been gagged by a powerful lobby of deluded ‘liberal’ ideo-logues and sex-trade profiteers.

As Autumn Burris, a former prostitute from California, who escaped in the late 1990s, told me: ‘I had to tell myself lots of things, lots of lies, in order to keep my brain from splitting into a million pieces and me going crazy with the continual abuse that was happening over and over and over, and the violence that goes along with prostitution.’ Autumn now campaigns for an end to the sex trade, and she runs training courses for police officers and other professionals on the realities of prostitution.

A survivor of the sex trade in Germany, Huschke Mau, put it this way: ‘Every time I met a john I had to drink not just one glass of wine but a bottle. If you’re sober and not doing any drugs you cannot make a (date) with a john. Once I stopped drinking, I couldn’t do it any more.’

If prostitution is tantamount to slavery, then why on earth do human rights campaigners and so many on the left support prostitution as a ‘job’ for women, and a ‘right’ of men? It all begins with the emergence of the campaign against HIV/Aids. It seemed, back then, to make sense to legalise brothels and pimping, and to create street-based ‘tolerance zones’ such as the one in Leeds. The ‘logic’ of this stance was that if you remove all criminal penalties, prostituted women will engage with support agencies, leading to 100 per cent condom use. This in turn will dramatically reduce HIV rates, argued the pro-legalisation lobby, and end the murder of women by pimps and punters.

This was the theory. But I visited a number of legal brothels in Nevada, Germany, Holland and Australia, and examined the claims made by the proponents of legalisation and what I found is that these arguments — the basis for our debate about prostitution today — simply don’t stand up.

Legalisation of prostitution in Germany, Holland and Australia has not led to a decrease in violence, HIV rates or in fewer women being murdered. I met a former ‘sex workers rights’ activist in Melbourne, Sabrinna Valisce, who, confronted with the reality of decriminalisation, had a dramatic change of heart. ‘I thought it would improve things if everything was legal and above board, but it just gave more power to the johns and the brothel-owners.’

What legalisation can mean is that the much-vaunted rights and freedoms which prostitutes are said to enjoy are instead claimed by brothel-owners and customers. It’s easy — they simply redefine themselves as ‘sex workers’ and reap the benefits. I have heard several pro-legalisation lobbyists describe themselves as ‘sex workers’ as well as pimps.

The true scale of the global sex trade is terrifying. I visited a village in India built entirely on prostitution and met a man who was pimping his daughter, sister, aunt and mother. I interviewed pimps in the legal mega-brothels of Munich, where men pay a flat fee which entitles them to use as many women as they want to. In Southeast Asia, I witnessed elderly male sex tourists from the UK pay for a ‘date’ with teenage girls in the ‘girly bars’.

I discovered that whatever the lobbyists say, women and girls in prostitution are overwhelmingly from abusive backgrounds, living in poverty, and otherwise marginalised. They are not free or empowered: they are abused and trapped.

Let’s not forget that this goes for boys too. During a visit to Los Angeles, I met Greg, born into a family with connections to the mob. From an early age he was sexually exploited and abused by powerful men. In his teenage years he met a pimp, and was sold for sex for six years before managing to escape. Greg has no truck with the idea that selling sex is part of homosexual culture.

I travelled to Amsterdam to interview the woman who coined the phrase ‘happy hooker’. These days, Xaviera Hollander runs a B&B named ‘Happy House’. I had assumed that she would have become rich and famous as a result of the stratospheric success of her book The Happy Hooker: My Own Story, which has sold 20 million copies worldwide. But in fact, as I soon learned over that dinner, it was selling other women that earned her fame and fortune. She told me that she was a hooker for about six months, just to learn the trade. ‘I went from a small apartment to a five-bedroom penthouse apartment in rocket time,’ she said proudly.

Hollander is a fairly typical representative of the ‘happy hooker’ myth we so often see in the media. But we buy into the lie because it’s convenient to believe it.

I have interviewed a number of punters, both in the UK and elsewhere, and this is the sort of thing they say: ‘I don’t want her to enjoy it — that would take something away from me.’ And: ‘I like prostitutes cos they do what I tell them. Not like real women.’ What about this: ‘It’s no different from buying a burger when you’re starving and the wife hasn’t cooked you anything.’

If I suggest to fans of prostitution that nothing terrible will happen to men if they can’t pay for sex, I hear the same complaints: ‘But what about disabled men? How will they get a date?’ When I point out that sex is not a human right, I’m told about the mother who bought her severely disabled son a prostitute for his birthday, and that a returning war hero who has lost his legs should have the ‘right’ to pay for a woman.

But consider all those millions of oppressed women. What about their rights? In one of the Nevada brothels I visited, the women were locked in at night, and barbed wire surrounded the high walls. In Seoul, South Korea, the women also used to be locked inside brothels all night — until a fire killed 14 young women in 2002. If battery hens were treated this way, there would rightly be an outcry from the same liberal leftists who often bend over backwards to defend this gross trade in human flesh.

During a brief trip to Auckland, I visited the street prostitution zone. New Zealand, we are regularly told, is the gold standard in dealing with the sex trade. The Home Office Select Committee (prior to its chair Keith Vaz being forced to step down following allegations that he paid for sex with young men) was looking at adopting a similar model of decriminalisation in the UK.

On the streets I met Carol, who looked 70 but was much younger, using a zimmer frame to rest between punters. Carol told me that since prostitution was decriminalised 13 years ago, nothing had improved for the women. The punters are still violent, and police still don’t care, she said. Nor do human rights defenders. While women all over the world fight to end violence and abuse, the Labour party and Amnesty International, to name but two public bodies, betray them.

The most effective way to brush over a terrible human rights abuse is to rename it. A pro-slavery strategist in the West Indies once suggested that instead of ‘slaves’, the ‘negroes’ should be called ‘assistant planters’. Then, he said, ‘we shall not then hear such violent outcries against the slave trade by pious divines, tender-hearted poetesses and short-sighted politicians’. The term ‘sex worker’ is just such a convenient gloss.

It was Barack Obama who said that human trafficking should be renamed ‘modern slavery’, so as to highlight the appalling conditions people were living in. Britain’s Modern Slavery Act was passed in 2015. It is founded on the idea that there is no place for ambiguity when you look at the circumstances of the people the Act is designed to protect: the conditions in which they live and their inability to escape their predicament.

The same applies to prostitution: it is not ‘sex work’. Most of the time, it is modern slavery.

If battery hens were treated this way, there would be an outcry from the liberals who defend this gross trade

Spectator.co.uk/podcast Julie Bindel and Rachel Moran discuss the plight of prostitutes. The Pimping of Prostitution: Abolishing the Sex Work Myth, is published on 28 September by Palgrave Macmillan.