A global investigation into internet child abuse has led to 50 arrests in Britain with dozens more expected, police said yesterday.

More than a third of the 360 suspects identified so far in an inquiry into an online paedophile forum live in Britain. Investigators believe that they will locate thousands more subscribers around the world.

The most recent arrest warrant in the inquiry, codenamed Operation Elm, was executed by the Royal Canadian Mounted Police in Winnipeg last week.

The Child Exploitation and Online Protection Centre (CEOP) said that 15 British children had been safeguarded from abuse. It said that the men detained in Britain included a firefighter, a university lecturer and a police community support officer.

Details of the inquiry were revealed as the internet forum’s “librarian” was given an indeterminate jail sentence at Teeside Crown Court.

Philip Anthony Thompson, 27, who is unemployed, had 241,000 indecent images of children on computer equipment at the home where he lived with his mother in Stockton-on-Tees, Cleveland. Some 3,000 were classified as depicting the most serious forms of imagery, including sadistic abuse.

Thompson pleaded guilty to 27 charges, including one of causing or inciting a child under 13 to engage in sexual activity.

Judge Michael Taylor told him that he would serve a minimum of three years and nine months in jail before being considered for parole. Thompson must also remain on the sex offenders register for life.

The judge said: “You have shown that you are a very dangerous individual indeed. I consider that you pose a very significant risk to the public and you are a dangerous offender.”

Thompson played a key role in maintaining the forum, which was established as a place where paedophiles could be introduced to one another.

He vetted images posted on the site in an attempt to ensure that they were suggestive of child abuse rather than direct portrayals of abusive acts. His aim, according to CEOP sources, was to keep the site legal and just “below the radar” to prevent it being shut down.

Subscribers to the forum were invited to post images and to make comments before being subjected to questioning by other users attempting to discover if they were undercover investigators.

Once they passed the vetting process, users were directed to other online channels through which they could exchange illegal images of child abuse.

Jim Warnock, head of operations at CEOP, said: “This site was not just about holding images, it was about a group of individuals who used this as a community to then jump off into other areas. It was a meeting point.”

Thompson, a self-taught computer expert, was trusted by other forum members to store their abusive images, which could then be used as “trading chips” to obtain other material. Jim Gamble, chief executive of CEOP, said: “This website — while appearing to operate on the margins of legality — was clearly a front for the sinister, sexual abuse of children and an image trading ground for paedophiles.”

The site was discovered by the Metropolitan Police’s Paedophile Unit in May last year. Their investigation quickly developed into a national and then an international effort involving 12 British forces and agencies in 33 countries.

Thompson was identified as a key administrator and placed under covert online and physical surveillance. Interviewers were coached for a month in techniques to make him talk before he was detained in a raid on his home.

Videos of his police interviews suggest that the tactics worked. Thompson appeared relaxed and smiling as he talked to the officers and admitted to being a senior administrator on the forum.

Detective Chief Superintendent Mark Braithwaite, of Cleveland Police, said: “Thompson was a critical piece of this network. He was, essentially, the librarian for a myriad of images that were distributed to like-minded individuals both in this country and elsewhere.”

Detective Superintendent Sue Knight, of the Metropolitan Police Child Abuse Investigation Command, said: “This is an example of the work we continue to do on daily basis to identify paedophiles and to protect children. Paedophiles need to be aware that they cannot hide their criminality behind pseudo-legal internet forums.”

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