A school teacher has been jailed for four and a half years for secretly filming his pupils and distributing sexual images of children over the Internet.

York Crown Court heard that Simon Mark Knowles, 52, had 19,541 indecent pictures and 174 indecent videos of children on his home computer. He had also made covert, non-erotic films of pupils at school and on school trips which he used for sexual gratification.

Some of the images he downloaded from the internet featured children as young as three to six years old. He also kept an adult sex toy at his school.

The Recorder of York, Stephen Ashurst, said: "To say there has been a wholesale breach of trust would be a very considerable understatement ."

Knowles, formerly of Harrogate but now living in Bridlington, pleaded guilty to five charges of possessing sexual images of children, some of it extreme, six of distributing sexual images of children, 11 of voyeurism and two of possessing child sexual images.

He was jailed for four and a half years, put on the sex offenders' register indefinitely, banned from working with children and made subject to a sexual offences prevention order controlling his use of the Internet.

Police have contacted the parents of all the children on the covert films. None of them were aware of the filming..

Knowles' barrister Paul Smith said he had lost everything through his behaviour.

Outside court 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.”

In a statement, North Yorkshire County Council said: “The school and the local authority have fully cooperated 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.”