A sex offender from Hitchin flouted a court order by working with youngsters after he was convicted of possessing indecent images of children.
Sam Sharma had been banned from working with children but continued to do so.
In a sick twist, his father is also to be sentenced with him later this year for a string of sexual assaults against an under-age girl.
Sam Sharma, 22, and Steven Sharma, 43, of Sanfoine Close, Hitchin, worked with children in Cambridgeshire and pleaded guilty to the sexual assaults before Cambridge Crown Court on May 25.
Reporting restrictions imposed by the court meant publication of their case has not been allowed until now.
In June 2010, Sam Sharma was convicted of possessing indecent images of children and voyeurism, for which he was handed a three-year community order and ordered to take part in a sex offenders’ treatment programme.
Just four months later he breached that order by working with children.
The offences he is to be sentenced for with his father took place before the conviction in 2010.
At the court hearing in May, Steven Sharma pleaded guilty to two counts of serious sexual activity with a 15-year-old girl, who cannot be named for legal reasons, between July 28, 2009, and September 1, 2009, and sexual activity with a 15-year-old between August 31, 2009, and September 14, 2009.
Sam Sharma was charged with two counts of sexual activity with a 15-year-old between January 1 and April 1, 2009, one count with another 15-year-old girl between April 30 and July 1, 2009, and another count with the same girl between March 31 and July 10, 2009.
The court heard how sex toys and underwear had been bought and sent to one victim.
About Steven Sharma, Judge Gareth Hawkesworth said: “Effectively there was a period of grooming followed by corruption of a minor.”
The father and son “acted independently” and did not know about each other’s offences, the judge was also told.
A date has not yet been set for their sentencing.