A former teacher has been jailed for downloading child porn on his work computer.

David Roberts, 48, had stored more than 600 pictures and films of children - including one image at the highest level of abuse.

Roberts, who was employed by Brighton and Hove City Council when his sick hobby came to light, had previously worked as an IT technician and photography teacher at a Brighton school, where he met his wife when she was a 15-year-old schoolgirl.

Roberts, of High Street, Newhaven, yesterday admitted 16 charges of possessing indecent pictures of children when he appeared at Lewes Crown Court.

Judge Anthony Scott-Gall, jailing him for 12 months, said: "You have an exceedingly unhealthy interest in young girls."

Roberts blamed obsessive compulsive disorder for his perverted need to collect the pictures.

As he was led to the cells he called out to the judge: "I think you have not understood anything about obsessive compulsive disorder and your sentencing today has been a complete farce."

Elizabeth Smaller, prosecuting, said the police launched an investigation after the council's technical support department, which monitors staff computers, alerted officers in June last year.

Roberts' home was searched and the indecent pictures from the internet were found saved on CDs and in printed form. The majority of images were movie files involving children between the ages of six and 12.

The police found two pairs of girls' knickers, as well as a bra and hair decorations.

Roberts admitted he had been viewing the child abuse images at work and then copying them on to discs and taking them home.

Ms Smaller said Roberts claimed one of the pairs of knickers were found in a car park in Brighton and the other belonged to his wife. His wife denied the pants were hers, but said the bra might have been.

She said she had been in a relationship with Roberts since she was a pupil of his at the age of 15. Roberts was 27 at the time. The couple split after his arrest.

Lewis Power, defending, said since his arrest Roberts had, "lost his wife, his job, his house and his community standing".

He said Roberts began viewing child pornography in 1998. and in recent years has become obsessed that he was a paedophile.

He said Roberts worked as a photography teacher at the secondary school before getting his masters degree. He had worked for the council for 15 years but lost his job when he was arrested and is now unemployed.

Roberts was made the subject of a sexual prevention order, which stops him contacting children on his release from prison. He is disqualified from ever working with children again and is banned from using a computer unless it is as part of his work.

He must not own a digital camera or mobile phone that can record moving images; he is prohibited from using the internet or possessing any picture of children without their parents permission; and he must not communicate by phone with a child or live with children without informing police.

He must sign on the sex offenders' register for ten years.