That catalogue of obscene photos and films was uncovered by a police raid on his then home in Forth, Lanark Sheriff Court heard last Thursday.
Robertson, 49, now of an address in Lanark, appeared on indictment for deferred sentence for collecting and possessing child pornography over almost a decade, from November 2005 until his arrest in April 2015.
The reason for the delay in him facing justice was explained in court by depute fiscal Ziad Hassan.
He said that Robertson had failed to appear in court for an earlier hearing of his case in March last year, and a warrant was issued for his arrest.
The authorities then lost track of him until police arrested him on February 1 this year, catching him in the act of breaching one of his original bail conditions by viewing the internet. However, in that instance, no obscene images were found on his computer.
The court had earlier heard from the fiscal that, in April 2015, after receiving information that a device registered to Robertson’s home in Forth had been used to download indecent images of children, police had gone there with a search warrant at 7am.
There was no one in, but the door was unlocked, and the officers, some from Police Scotland’s cybercrime unit, found a hard drive and a Dell laptop in the living room with the indecent images of children on it. He was later interviewed by police and charged.
The then BT engineer was a first-time offender, the court heard.
His solicitor, Archie Hill, told the court that his client had searched for the images late at night and under the influence of alcohol while his wife and children slept, unaware of his actions.
His exposure had had a devastating impact on his life as he’d lost his job and his home and his wife is seeking a divorce, said Mr Hill.
Robertson had made three unsuccessful suicide attempts, twice by hanging and once by a drug overdose, he said, adding: “He will have to live with the consequences for the rest of his life.”
The solicitor admitted that, in an interview with social workers, Robertson had tried to minimise the sexual gratification he’d received from the images, preferring to blame his actions on inquisitiveness. That angered Sheriff Nikola Stewart, and she said: “We are talking about babies here. It is disgraceful and disgusting. It is a ridiculous excuse for his conduct, and he is not going to get away with it.
“He doesn’t even begin to address his issues and never will until he owns up to them.”
She was also dismissive of Robertson’s claims to social workers that his actions could be partly blamed on abuse he said he himself had suffered as a child.
Addressing Robertson directly, the sheriff described his actions and attitude to his offence as “utterly, utterly despicable” and said he was guilty of “dehumanising” the children in the images. “Those who seek out this depraved imagery are the equivalent of child abusers,” she said.
She put Robertson on the sex offenders’ register for five years and gave him a three-year community payback order including 200 hours of unpaid work and a 7pm-to-7am home curfew for four months.