A married female tutor had sex with a 13-year-old boy during a lesson at his home then abused him for the next two years, a court heard.
Carolyn Keeling, 64, allegedly smoked cannabis and drank wine while teaching the boy, who she is said to have abused between 1993 and 1996.
She denies the claims.
Gloucester Crown Court heard Keeling stripped down to her underwear to sunbathe during an outdoor lesson on blankets outside the boy's home.
She started touching the teenager through his shorts and the pair later had sex with a condom she provided from her 4x4 car, a jury was told.
The incident was allegedly the start of abuse that lasted two years and involved Keeling having sex with the boy at least 100 times.
Prosecuting, Ed Burgess said the boy disclosed the abuse to his mother in 2012, after reading of the Jimmy Savile scandal.
He reported the alleged offences to police in April 2014. Keeling, of Taynton, near Gloucester, was charged with six counts of indecent assault, which she denies.
"He talked about her as 'Mrs K'," Mr Burgess said. "He described her as being hippy-like in her mannerisms, in the way she behaved and dressed.
"He thought she was rather cool.
"He was a prematurely mature boy physically.
"He talks about his hormones raging and he wasn't going to turn down what she was offering.
"At the time he didn't see it as abuse, he rather enjoyed it.
"It was only later that he came to understand it as the sexual abuse that it was."
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The court heard Keeling was so trusted by the boy's family that she was given a key to their home and let herself in to give him lessons.
She would sometimes go in to the boy's bedroom - where he would sleep naked - and wake him up by getting in to bed with him, it is alleged.
It was also claimed keen horse rider Keeling would take the boy on nature walks and rides as part of his "rural sciences" work.
"They went out riding, dismounted from the horses and had sexual intercourse against a tree on one occasion," Mr Burgess said.
The alleged abuse stopped when the boy stopped his education at the age of 15 and left home to work.
"He liked Carolyn Keeling as a person and but for her he wouldn't be able to read or write and do basic maths in the way he can in adult life," Mr Burgess added.
The boy contacted Keeling when he was in his 20s to ask for a reference for a permanent job and the pair twice met to have sex, he added.
The boy, now in his thirties, told his mother that he had been in a sexual relationship with Keeling, in 2012.
"In about September or October 2012 the Jimmy Savile story was all over the news," Mr Burgess said.
"His mother received a phone call.
"She recalls how her son phoned her and was talking about the Jimmy Savile case.
"He said he had had sex with Carolyn Keeling when she was his tutor.
"His mother had no inkling there was anything amiss."
The boy contacted a sexual health centre in Gloucester in April 2014 and asked for the abuse to be reported to police.
In police interview, Keeling described the boy as "intelligent" and "bright" and said she would let herself in to his family home with a key.
She told officers the boy slept naked and she would sometimes go into his bedroom to wake him up for lessons.
"She said there may have been some unintentional contact with his bottom but nothing more than that," Mr Burgess told the jury.
"She would take him out in her car as part of his education.
"Rural sciences was part of his education and they would go walking together."
She told officers she had a degree in personal, social, health and economic (PSHE) education and would talk of personal sexual experiences to teach pupils.
After the allegations were revealed, she described herself as "gobsmacked", Mr Burgess said.
The alleged victim told the court of the first time Keeling allegedly had sex with him.
"It was hot," he said.
"She had a bottle of wine in her car, which she went and got.
"I ended up in a pair of boxer shorts.
"She said 'do you mind if I take my top off, it's just the same as a swimming costume?'.
"I was a young lad.
"I wasn't going to say no to that situation.
"She was in her bra and a pair of knickers.
"I started getting aroused, she had a laugh about it.
"One thing led to another.
"She went to get a condom from her car."
The man said he did not report the abuse until 2014 as he saw Keeling as a friend.
"I didn't want to look at it in the light of what it basically was," he said.
"It was an adult sleeping with a child.
He said he had decided to come forward after thinking about a "45 to 50-year-old" having sex with a young teenage boy.
"I would want them hung, drawn and quartered," he told the court.