While Teesside Crown Court Judge Michael Taylor found that Philip Thompson, 27, was a public risk, he gave him an indeterminate prison sentence with a minimum of three years and nine months, The Times of London reported.
"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," Taylor told Thompson.
Prosecutor Harry Hadfield told the Times Thompson was arrested by police after they raided his home in the town of Stockton-on-Tees. Inside the home was a collection of 241,000 photographs of child abuse.
Hadfield called that "one of the largest seizures of indecent photographs in the U.K."
The Times said under the current sentence, Thompson could become eligible for parole if he can prove he is no longer a threat to the general public.