Christopher Dunn (39) met the alleged victims while working at Leicester’s Soar Valley Music Centre, Claremont Street, Belgrave, which is run by his parents.
Dunn, who was the centre’s development manager, also taught music, played in the orchestra and on occasions conducted it.
He is a former organiser of the county’s Glastonbudget tribute band music festival, from 2007 to 2009.
Leicester Crown Court was told on several occasions, Dunn drove one of the 15-year-old music centre students into the countryside for intimate encounters, involving kissing and sexual touching.
Vanessa Marshall, prosecuting, said: “She recalls one occasion when she wanted to change out of her uniform into her day clothes, the defendant said ‘I like the school uniform’.
“These trips varied from 10 minutes to two hours and she was taken to the defendant’s boat moored in Thurmaston Marina.” The court heard that another 15-year-old had a relationship with the defendant at a different time, allegedly involving sexual touching at his parent’s home or in his car.
After her 16th birthday, she lost her virginity in his car. They also had sex on his boat.
On another occasion, the defendant allegedly twisted a 15-year-old girl’s nipple over her top, while tackling her for the ball during a sports game. She later challenged him about it. Dunn told her: “I didn’t think it was you.” He said he thought it was someone else (one of the boys).
Prosecution witness, Michael Norman, told the jury that on an overseas tour, he walked into a hostel bedroom he was sharing with the defendant and saw a 16-year-old girl – not the subject of any charges – straddling Dunn as he lay on the bed, both fully dressed.
The girl later complained about Dunn to his mother, while on the tour, and she began investigating the matter. Mr Norman said: “He was worried and said it could be damaging for his career, if her allegation was made public.”
However, the girl later withdrew her complaint.
Dunn, of Pulford Drive, Thurnby, denies seven sex offences alleged to have taken place between 2000 and 2008, when he was in his late 20s to mid-30s.
“We say he was in a position of trust and sexually abused three girls between the ages of 15 and 16,” said Miss Marshall. “He’s the son of Elizabeth Dunn, the director of the music centre, which is a charitable institution providing education and performance opportunities in music for all ages.
“Dunn was looked up to, especially by young female students. It’s not alleged the defendant forced any of these girls to engage in sexual activity against their consent. But that’s no defence because the case is he was embarking upon inappropriate relationships with young girls when he should have known better.”
She said that in 2003 it became illegal for someone in a position of trust to engage in sexual activity with anyone under 18.
At 15, the girls were also below the legal age of consent.
A concerned parent also made an official complaint to the centre, and at a safeguarding body at a school, about the ethics of Dunn being in a relationship with a 17-year-old music centre pupil – not a subject of the charges – after the time of the alleged offences. When interviewed in 2012, Dunn, who qualified as a music teacher in 1999, said the centre was a “community organisation” and not a school.
He denies three counts of indecent assault against one 15-year-old, two counts of sexual activity with a child under 16 and one of sexual activity with her when she was 16, by a person in a position of trust and sexually assaulting a third girl, by twisting her nipple.