A paedophile caught with graphic pictures of children engaged in acts of incest was jailed for 15 months after his girlfriend found evidence on their computer.
Nicholas Green, who moved in with his parents in Antoneys Close, Pinner, after the discovery, pleaded guilty to 17 charges of possessing indecent images and three of distributing them.
In total the 32-year-old had 156 photos on the computer, including an image of a 14-year-old boy having sex with his mother while his 12-year-old sister watched.
Robert Meikle, prosecuting, said: "On April 27 this year the defendant's partner went on the computer she shared with him while he was away at work.
"She noticed he had logged on to an internet site and there was a list of communications between the defendant and another person.
"She examined the details and they disturbed her. One message asked 'have you ever been with a 10-year-old?'
"She telephoned the defendant and asked 'who the hell have you been corresponding with on the computer?'
"He returned home and let himself in and went straight to the computer and said he had done nothing.
"He then went to report himself to the police."
Judge Susan Tapping condemned Green's actions at the hearing at Harrow Crown Court last Wednesday.
She said: "I have no doubt whatsoever that the children who are the subject of these images have themselves suffered serious abuse and the only reason they suffer this abuse is because people like you can be sexually gratified by looking at these images.
"Not only have you downloaded them and viewed them for yourself but you have been involved in distributing them to other like-minded individuals. You were only discovered because your partner at the time, your partner of eight years, discovered what you had been doing.
"You have lost a great deal because your relationship has broken down."
Green was also ordered to sign the Sex Offenders Register, which he will remain on for the next 10 years, and has been banned from working with people under 18.