Police officers have been filmed for the first time going undercover as they hunt down child sex offenders.
A new three-part documentary starting tonight follows “Simon” as he goes online offering his 10-year-old daughter to abusers.
But in reality “Simon” is an undercover police officer, the Mirror explain.
And “Simon” spends his days trawling chat rooms as he hunts down paedophiles.
The covert operative said: “Simon is completely fictitious, he's a character. When I go in to role and deploy he comes out of a box and he's like a skin that I put on.
“It's quite disturbing portraying yourself as an adult, male, paedophile, but it's such a good technique for catching people who are seeking to abuse, hurt and rape children.”
Speaking ahead of Channel 4's ‘Undercover Police: Hunting Paedophiles’ Simon Bailey, the National Police Chief 's Council spokesman on child protection, called on big tech firms to take responsibility for the huge surge in abuse, with police "overwhelmed" by the number of cases.
He said companies like Facebook are "not doing enough" to prevent the uploading, sharing and viewing of child abuse images.
"I don't think their role in all this has been truly appreciated because without them the abuse wouldn't be able to take place in so many cases," he said.
"It's the big market leaders that actually bear responsibility for making sure the internet is a safe place for our children and for our grandchildren to go. And ultimately at this moment in time it's not safe."
Mr Bailey blamed the "staggering increase" - from 7,000 indecent images of children in 1990 to 17 million on the child abuse image database now - on the development of the internet.
The film follows the officer as he exchanges sick messages on the children's section of an open website called Chat Avenue.
Spotting that abuse videos are openly being sold on the site, Simon says: “It's not even hidden is it? You'd think it would be a bit more covert, but this is in a child's chatroom.”
He eventually agrees to introduce a member called “Bodycount” to his daughter “Jess” and invites the target to travel to Norfolk from his home in Burnley.
The suspect is identified as convicted child abuser Graham Marshall, 36, and local plain-clothed police arrest him.
Asked how he sees his future, Marshall tells the filmmakers: “Bleak at the moment because I can't change what I'm doing.” He was later jailed for four and a half years after pleading guilty to a string of child sex offences.
Later Simon deploys to the dark web where he sees images distressing images involving a baby, causing him to stop work and take advice from his controller.
He tells her: “I'm feeling a bit choked now talking about it.”
His manager says: “You remember what you have been seeing and that's real life. What you don't want is you going home to your family and kids with that playing in your mind.”
Simon tells the film: “There are some really distressing things on there but it's tremendously satisfying to identify just one offender or safeguard just one child.
“Once in a career would be enough, so to do that daily feels incredible. For me it's the best job in the world.”
Mr Bailey warned parents to keep a close eye on their children's internet usage.
He said: "I could describe to you some of the most horrific videos where you can see a child that's been groomed, abusing themselves within their own bedroom and you can hear their mother calling up and recorded on the video, 'darling, dinner's nearly ready,"' said Mr Bailey.
"Now that is pretty horrific, I think, in anybody's estimation."
Hunting Paedophiles is on tonight on Channel 4 at 9pm
