A convicted paedophile arrested during a police sting and another hunted in Margate are just some of the sex offenders highlighted in a television documentary this evening.

Graham Marshall had bought a £132 rail ticket so he could have sex with a 10-year-old girl.

But before he could board the train, undercover cops raided his home and arrested him.

Marshall, wearing a pink T-shirt, was handcuffed and marched out of his home and into a police car where he was taken to the police station and quizzed by officers.

Throughout interrogation he stonewalled every question with the same stock answer: "no comment." He was later jailed for four-and-a-half years after admitting a string of charges including inciting sexual activity with a child.

The shocking footage and the painstaking work of detectives will be shown tonight in the first 90-minute episode of a hard-hitting three-part television documentary.

Undercover Police: Hunting Paedophiles follows officers working in Kent Police's paedophile online investigation team and will be shown on Channel 4 at 9pm.

It features detectives trying to track down another suspected paedophile who scrawled a message on a wall inside the gents' toilets on Margate seafront offering naked photos of a child.

Officers finally tracked him down using his email address and mobile phone. In a police cell he told officers he had no intention of sharing photographs but just wanted to "talk to other like-minded people." One of the investigating officers said she didn't believe him.

When he appeared in court he pleaded guilty to making, possessing and distributing indecent images of children and was given a two-year community order and paced on the sex offenders' register for five years.

Chief Constable Alan Pughsley said: "First and foremost, this documentary should serve as a warning to parents and guardians about the dangers to children and vulnerable people using chat forums and other online services unsupervised.

"If, as a result of this important and impressive piece of film-making, just one potential victim is safeguarded then it has been a success."

'These programmes also shine a light on an extremely complex and sensitive area of policing...'

But he warned: "These programmes also shine a light on an extremely complex and sensitive area of policing. I’m very proud of my officers who are featured. They are often exposed to some unimaginable things and they carry out their work with a great sense of purpose and courage."

The programme is the culmination of three years’ work where producers and camera crews were embedded with Kent's paedophile investigation team and officers from the Eastern Region Special Operations Unit.

It is the first time filming of undercover operations like these has taken place and follows an undercover cop called "Simon" who trawls chat rooms on the internet trying to trap sex offenders.

At one stage one of the officers breaks down as he is reminded of seeing pictures of a tortured baby. He said: "It was horrible, nasty, really nasty. I think we'll move on."

Officers were horrified to discover Marshall, who used the name "Bodycount" on the web, had previous convictions for possessing "extreme pornography" and had been given three-year community rehabilitation order after admitting indecently assaulting a female aged under 14.

In an interview in his cell he says his stepmother threatened to kill him when he was a boy but he "never told." He admitted: "My future is bleak. I can't seem to change what I am doing."

Filming began in March 2018 with camera crews shadowing officers as they carried out inquiries, made arrests and examined evidence. Tonight's episode is broadcast the day before national Safer Internet Day.

Executive producer Joe Mather said: “This is a hard-hitting trio of documentaries filmed with great care and sensitivity over two years. It’s been extraordinary to have been granted access to such a complex area of policing and to witness the work of undercover detectives as they go about searching for paedophiles operating online.

"What the child sexual abuse officers see on a daily basis is truly horrific. Yet these detectives, often with children of their own, have to engage with the offenders to find and arrest them knowing that for every one they arrest there are countless more victims still at risk.”

Police launched a new strategy of undercover cops in 2017 following a raft of high-profile vigilante "paedophile hunter" stings.

The explosion in online child sexual abuse has become even worse during the coronavirus pandemic with reports of obscene material doubling to more than four million in the first month of last year's lockdown.

In April there were nearly nine million attempts in the UK to access child sexual abuse websites which had been previously blocked by the Internet Watch Foundation.

In the UK, 300,000 people are considered a threat to children, either through physical abuse or online.

Alisa Pomeroy, Channel 4's senior documentary commissioning editor, said: “The extraordinary level of access given to us by Kent Police provides a new appreciation of the complex and vital work being done by undercover detectives as they go about searching for paedophiles operating online."

The other hour-long episodes will follow on February 15 and 22.

To get the latest updates in ongoing cases, police appeals and criminals put behind bars, click here

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