Paul Farrell, who worked at the central London children’s hospital between 1994 and 2020, is due to be sentenced for a catalogue of crimes against eight victims.
The 55-year-old, who used an area at the hospital for abuse but did not target patients, befriended the parents of his victims and acted as a babysitter or lodger in order to abuse their children.
Prosecutor Paul Douglass told Wood Green crown court Farrell had “ruthlessly exploited the vulnerabilities of his victims” and was able to win the trust of their parents.
“The total number of offences to which the defendant has pleaded is not less than 560 over a period of 35 years – the true figure is likely to be in the thousands”, he said.
In a statement to the court, one of the victims – whose brother was also preyed on by Farrell - said: “The last 18 months of my life have been unrecognisable and torturous.”
The victim said he had felt “guilt, shame, despair and disgust” at what had happened since making the complaint to police, as he detailed struggling with depression and in the relationship he had with his family.
“I now feel hopeless, lost and disgusted at my silence that has allowed you to ruin the lives of so many innocent children,” he added.
“Innocent children like me and my brother will be profoundly scarred by your actions for the rest of our lives.”
Mr Douglass told the court that the victims had not previously reported the abuse because they had a “sense of shame” of what had happened, while some feared that their own parents would suffer the consequences.
“The defendant used a combination of bribes and threats which enabled him to commit serious sexual offences against the same victims, sometimes for many years,” the prosecutor said.
“He never gave his victims the slightest indication that he knew that what he was doing was wrong.
“For many of them, the sexual abuse became routine. He exerted complete control over his victims, and sometimes their families.” Farrell was arrested for the first time in January last year after one of the victims saw a picture of the defendant on Facebook, which showed him to be around children.
He has admitted offences between 1985 and 2020, include attempted rape, sexual assault of a child under 13 and making indecent photographs of children. He faces sentencing over the two-days for 76 offences, encompassing large numbers of incidents of abuse.
A spokeswoman for Great Ormond Street Hospital (GOSH) said their thoughts were with all the victims of “this horrendous abuse” and that Farrell had “admitted to a catalogue of truly awful crimes”.
She added: “His actions are in direct contrast to everything we stand for as a children’s hospital.
“We would like to reiterate what has been said in court; that Paul Farrell did not target children at GOSH.
“We urge anyone who has concerns about this case to call the helpline that we have set up with the NSPCC on 0800 101 996.”
Farrell, from Camden, will be sentenced at the end of the two-day hearing on Friday.