A "sick and depraved" primary school teacher has been jailed after he filmed students as they changed for swimming and shared the images on the internet in "a level of betrayal rarely seen", police said today.
Simon Mark Knowles, 52, formerly of Harrogate, North Yorkshire, but now living in Bridlington, was sentenced to four-and-a-half years' imprisonment after pleading guilty to 24 charges at York Crown Court.
They included making indecent images of children as young as three, possessing indecent images of children, distributing indecent images of children and recording a person doing a private act.
North Yorkshire Police said some of the children he filmed were students at the North Yorkshire school where he taught.
Officers investigating the case found 19,541 indecent photographs of children on Knowles' computer along with 174 indecent videos, the force said.
They also found evidence that he had distributed 147 indecent photographs of children. The offences took place from 2009 up until his arrest in April 2012.
Following Knowles' sentencing, Detective Sergeant Mark Jackson, of North Yorkshire Police, said: "On the face of it, Simon Knowles was a well-liked teacher who had the respect of his colleagues and aspired to be an assistant head teacher.
"In reality, he was a calculating and deceitful man who completely abused his position of trust for his own sexual gratification.
"The level of betrayal, falseness and dishonesty he has displayed over a number of years is rarely seen.
"He filmed innocent children while they were getting changed, using covert methods which highlights the lengths he was prepared to go to indulge his twisted fantasies.
"The fact that he was also sharing images on the internet, some of them at the highest level of seriousness, shows that Knowles is a sick and depraved man who I am extremely glad that we have caught.
"He betrayed his family, his colleagues, his profession and, ultimately, the children he was entrusted to educate and their parents.
"He has shown no remorse for his actions throughout the investigation which was a long and difficult process for the officers involved, everyone connected with the school and, of course, his victims.
"Simon Knowles is an intelligent man which makes his conduct all the more abhorrent and quite frankly prison is the best place for him."
After the hearing, North Yorkshire County Council said in a statement: "The school and the local authority have fully co-operated with the police throughout the investigation, and the school has supported parents throughout this terrible ordeal.
"Child protection remains the highest priority for the county and all proper child protection procedures and safeguards are followed by the local authority when employing staff to work with children."
Knowles will have to register as a sex offender and will be banned from working with children.