A 25-year-old man downloaded indecent images of children while he was taking part in a sex offenders' programme, Worcester Crown Court was told.
Matthew Day had found a way to bypass the block which had been placed on his computer, said Nicolas Cartwright, prosecuting. He eventually confessed to his probation manager. He had concentrated on girls aged 13 to 16 and in school uniform and bikinis.
Day, of no fixed address and formerly of Droitwich Spa, pleaded guilty to possessing indecent pictures and breaching the terms of a three-year community order imposed in June 2011. He was jailed for 12 months.
Recorder Adrian Redgrave QC said Day had been given a chance when the community order was made. "In a very short time from the previous order, the defendant was at it again," he said. "These offences are very disturbing."
In 2011 Day had admitted downloading 145 indecent images, some of the worst type. The community order had been made to put an end to Day's behaviour. He added: "It didn't. He simply carried on despite the efforts of the probation service and his family.
"The community order didn't stop you last time. There is no reason to think it will stop you again. What may stop you is prison."
Lee Egan, defending, said Day had spent five weeks in custody. He submitted the fear of prison was sufficient to prevent future offending. Although he had the support of his family, he conceded that the offending had ruined his life.
Recorder Redgrave made a ten-year sexual offences prevention order. The court was told that Day had already registered as a sex offender.