Jason Hardy, 46, of Dovecote Drive, Little Addington, was jailed for three-and-a-half years in 2011 for possessing indecent images of children.
But at Northampton Crown Court yesterday (September 24), a judge heard how, in July this year, Hardy had found an SD card in his house that police had never found when he was first prosecuted.
The court heard he knew it had a "50-50 chance" of holding more indecent images.
Less than a week after the discovery, Northamptonshire Police visited Hardy on a routine check-up as part of his existing sexual harm prevention order.
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Hardy's defence barrister told the judge: "The officers asked him if there was 'anything they should know about'. At which point [Hardy] left the room and returned with an SD card.
"He told the officers he had found in a drawer earlier that week and it had a '50-50 chance' of containing indecent images from before he was jailed in 2011."
Officers examined the memory card and found it held four 'Category A' videos – the worst possible classification for indecent images.
Hardy claimed he did not use the memory card or view its contents once he found it.
His Honour Judge Michael Fowler QC told Hardy: "I'm satisfied these images were downloaded from before you were last sent to prison.
"But there is an element of culpability. The police were at your house for an unannounced visit and you did not surrender the item immediately. There must be some form of punishment."
Hardy was handed a community order for 12 months, 75 hours of unpaid work and 30 days of rehabilitation. His sexual harm prevention order will remain indefinitely.
The memory card was ordered to be destroyed.