A 61-year-old sex offender who spent more than decade building up a DVD library of women and girls he filmed in public places was caught after he was spotted filming a 12-year-old girl at this year's Lord Mayor's Procession.

A 61-year-old sex offender who spent more than decade building up a DVD library of women and girls he filmed in public places was caught after he was spotted filming a 12-year-old girl at this year's Lord Mayor's Procession.

Trevor Chatters used a concealed camera, stockpiling images at home for his “sexual gratification”, Norwich Crown Court heard on Monday .

He also kept a record of every school in the country and attended cross country school meetings to seek new victims.

His behaviour came to light after he was spotted filming a 12-year-old girl watching the Lord Mayor procession in July.

Chatters was foiled by the boyfriend of the victim's elder sister, who alerted police and helped them grab his camera.

The court heard he would unzip the camera bag with the lens exposed and use it to film unnoticed.

Chatters, of Coronilla Green, Gorleston, also pleaded guilty to a charge of committing an act of outraging public decency by filming a woman at Piccadilly Circus tube station in London on June 28.

He was sentenced to spend three years completing the Thames Valley specialist sexual offenders' rehabilitation programme, and was banned from having any photographic or recording equipment in public anywhere in England and Wales.

Judge Alistair Darroch said: “This is offensive, upsetting behaviour and it has got to stop.”

The court heard Chatters, who has no family and lives alone, had previous convictions for threatening and disorderly behaviour and for indecent exposure.

In mitigation Michael Clare said: “He says he is unable to stop his offending behaviour without help. It's not something he wants to carry on doing, but without help he won't be able to help himself.

“He doesn't seek to have contact with, hurt, or contact anybody.”