In 2015, police entered the home of Alain Charlwood-Collings, a 39-year-old man from Tiverton in Devon. On his home computer they made a horrifying discovery: more than 100 hours of live-stream footage of 46 different children being sexually abused thousands of miles away, in the Philippines.

Yet it was not until almost three years later – when Charlwood-Collings was already six months into an 18-year prison sentence – that the Philippine National Bureau of Investigation’s anti-human trafficking division finally swooped on a small house in Tacloban City in the eastern province of Biliran.

Inside, they found their prime suspect: a local woman, who was in the act of abusing two young girls, directed and watched by a foreign man on Skype.

Days later, police made a second raid on a house 150km away, where a second woman found to be running a 24-hour cyber-sex den was arrested. Nine children and six adults were recovered from the house.

Over the course of 10 years, the two women had been paid £33,000 by Charlwood-Collings for procuring children as young as four and filming their rape and abuse. Some of the 46 children involved were the women’s own children or sisters. Others were the children of neighbours, or from the wider local community.

Convicted paedophile Alain Charlwood-Collings. Photograph: Devon police

The raids were the culmination of a complex and lengthy joint operation between Devon and Cornwall Police, Britain’s National Crime Agency and the Philippine authorities.

Throughout the investigation, Philippine officials also received help from another unlikely source: a former police officer from California who, leaving his comfortable life behind, had crossed the world to join the fight against the cyber-sex traffickers.

Derek Seeker – not his real name, but the one used by his employers to protect his identity – spent a decade working on narcotics, gang crime and sexual assault cases before quitting to join the International Justice Mission, an anti-trafficking charity that operates in 10 different countries.

Here in the Philippines, Seeker works as one of IJM’s small, secretive band of special investigators, former law enforcement professionals, who help to seek out and bring to justice those selling children online. There are IJM special teams all around the world working to support state authorities in seeking out traffickers and freeing children from slavery, the majority local men and women. In the Philippines there are a higher number of foreigners on the IJM payroll, due to the international nature of the cyber trafficking crimes being committed here.

That Seeker is here at all is indicative of the huge resource and training gap that is hobbling the capacity of police in the Philippines to respond to the cyber trafficking epidemic they face.

In the past decade, the Philippines has become a global capital for online child sexual exploitation.

Members of the Philippine National Bureau of Investigation are seen during Operation Aero, which led to three arrests. Photograph: Courtesy of IJM

There are a number of reasons the Philippines has become a destination of choice for online predators. The country has a long-established sex tourism industry that has normalised the purchase of cheap sex by foreign men. About 20% of its population of 103 million people is living in poverty. English is widely spoken, and roughly 50% of the population owns a smartphone. Advancing camera phone technology is making encrypted live-streaming possible even in the remotest of communities. Anonymous wire money transfers are standard.

Above all, there is demand.

“We’ve just seen a huge, exponential rise in perpetrators seeking to abuse children online,” says Rob Jones, director of vulnerabilities for the National Crime Agency in the UK. The Home Office has estimated that 80,000 people in Britain alone pose a sexual risk to children online. “Anyone with a smartphone can now engage, purchase and direct the abuse of children, and this abuse is usually very severe.”

Jones says that children in countries like the Philippines are increasingly at risk.

“For abusers, accessing children from poor communities in developing countries means that they don’t have to travel, they can avoid border controls and the financial transactions are very small, sometimes only $10 or $20 a time, so it’s almost impossible to track. These countries don’t usually have enough capacity to monitor or investigate these crimes, so it is less risky. ”

The scale of the Charlwood-Collings case shook even experienced specialist police officers assigned to the case.

“It was a very chilling case because of how many children he’d managed to abuse before we got to him,” says Detective Inspector Andrea Kingdon, from the Devon and Cornwall police paedophile investigation team.

“In total, we found 102 hours of footage in the suspect’s possession, and we were able to identify 46 different children in 107 individual files and 2,000 images of child pornography. In some of the pictures we also identified Charlwood-Collings abusing a child in the Philippines, so we knew that he had also gone there himself.”

Kingdon said that even though he’d destroyed dozens of young lives, Charlwood-Collings had never shown a minute of remorse.

“Throughout this investigation we’ve all been acutely aware that even though we’d locked this individual away, there are untold numbers of others like him out there and it was likely that the children in the footage were continuing to be abused.”

Seeker has now worked on multiple cyber trafficking cases since he arrived in the Philippines in 2016. Most have involved foreign men – in four cases, British nationals – many of whom have exploited multiple children over extended time periods.

What differentiates the Philippines from elsewhere is that many of the children involved are being abused in their own homes, by their own parents, for financial gain.

“There’s a long history of foreign men buying sex here in the Philippines and poverty is also a huge factor,” he says. “But I don’t think you can put it just down to this. When you go into really poor rural communities, a large percentage of people there find this despicable. In the houses we’ve raided, they’re actually not always the poorest. Sometimes it’s just about wanting fast money.”

IJM has poured millions into helping fight the cyber sex industry in the Philippines. The organisation has trained social workers – all local and the majority women - and has its own criminal prosecutors to help get cases to trial.

Yet its use of special investigators takes IJM out of normal NGO safeguarding territory and into direct collaboration with law enforcement. The organisation trains national and local police, and provides hardware like cars and support vehicles to support raids, and computers and software that enables under-resourced local forces to track cyber crimes.

Seeker also uses his background in criminal investigations to assist with what he terms “traditional field investigations”.

“IJM has no authority on its own but, working alongside the police, we can contribute an enormous amount,” he says.

“The police here are undermanned and these are complex investigations. In the west, most cyber investigations rely on IP addresses and information from internet service providers, but in the Philippines this information doesn’t get you very far. A lot of these crimes are committed on mobile phones or in rural and provincial areas, and it isn’t easy to get arrest warrants – so your evidence needs to be really tight.”

Before 2016, there had only been two convictions for cyber trafficking in the Philippines. This year alone, IJM have partnered with the Filipino authorities to rescue more than 120 child trafficking victims, arrest 44 perpetrators and secure 21 convictions.

“In the Philippines there are very strong laws against trafficking and, once we have started enforcing these laws and perpetrators are beginning to understand that they could go to prison for the rest of their lives, then we’re seeing a huge reduction in the areas we’re working in,” he says.

Is it right for an NGO to be taking such an active role in police operations?

“It’s our mission to work ourselves out of a job and get to the stage where we’re not needed or helpful any more,” says Seeker. “We have no authority on our own, everything is done to support the existing work of the National Bureau of Investigation and the Philippine national police.”