The 49-year-old, who cannot be named for legal reasons, spent Monday in the witness stand of Southwark Crown Court giving explicit testimony of her decade and a half of alleged sexual encounters with the Australian entertainer, more than 30 years her senior.

At one stage, she claimed, he abused her when his own daughter was asleep a few feet away in the same room. “He didn't feel inhibited, I think he got a thrill out of it,” she said.

But for many years she was too shy, “mute” and terrified to complain, or tell anyone what was happening to her, she told the court.

Harris, 84, has pleaded not guilty to 12 charges of indecent assault.

Seven of those charges relate to the complainant in the dock on Monday.

In a low and nervous voice, sometimes sharp with anger but more often a dulled monotone, the complainant gave evidence from behind a screen that hid her from Harris’ and the media’s sight.

She said her family lived diagonally opposite the Harrises when she was young, and she was friends with Harris’ daughter Bindi from the age of about two or three.

She went on holiday with the Harris family to Canada, Hawaii and Australia at the end of 1978, sunbathing and snorkelling.

In Hawaii she was taking a shower in her hotel room and emerged wrapped in a towel to find Harris in her room.

“He came over to me and gave me one of his big hugs and tickles,” she said – which he had done before and she never liked because she found it “a bit creepy” and “cringey”.

“Rolf would enfold me in his arms then just tickle me up and down all over my body.”

But this time he went further – he put his fingers inside her. “I was shocked and terrified,” the complainant said. “I didn’t know what to do.” After Harris left the room she sat on the end of her bed “in a state of shock, really”.

Harris abused her several more times during the holiday, she said, sometimes only metres away from his unsuspecting wife and daughter.

The complainant said she was an “excruciatingly shy” child and was worried that if she told anyone what happened it would “cause mayhem”, so she never did.

Once she was woken by the click of a camera and discovered Harris standing over her with the camera. Years later he told her that her flesh-coloured bikini turned him on, she said.

“I felt disgusting in myself for letting him do it,” the witness said. But she was too scared of him to say anything to anyone. “I just buried it,” she said.

When she returned to the UK she started stealing gin from her parents to deal with her confusion and anger over what had happened, and her panicky feelings when Harris would come to visit.

She told of several times that Harris would visit her home and assault her when she was alone in a room. He also attacked her twice when she visited his house to stay with Bindi, she said - this time also performing oral sex on her.

One of those times Bindi was asleep in a different bed in the same room.

She would pretend to orgasm because "I thought that was the only way to stop him".

Another time he masturbated over her while she lay in bed, and put his hand on her head attempting to get her to perform oral sex on him.

"I thought it was all my fault," the complainant said. "Because I didn't stop him. I should have shouted and screamed. (But) I lost all my self-confidence."

When she was 19 she was in a small swimming pool at the Harris' house in Bray when he joined her in the pool and started to touch her.

Their sexual encounters continued into her 20s. “I didn’t say specifically that I don’t want anything but my actions should have shown him,” she said. She denied every throwing herself at him, flirting or making sexual remarks.

She drank “to blot it out”, she said.

In 1994 Harris sent her a postcard telling her about a bout of vertigo he had suffered. The front of the card contained “disgusting” jokes of a sexual nature, she said, and she hid it from her parents.

Prosecutor Sasha Wass QC read some of the jokes on the card, titled “All I need to know about life I learned from my dog”. They included “if you stare at someone for long enough you will get what you wish”, “when it comes to sex if at first you don’t get what you want, beg”, and “be aware of when to hold your tongue and when to use it”.

One time she invited him to her flat because she wanted to talk to him about Bindi, but instead “he just said ‘where’s the bedroom?’” she said. Another time she visited him backstage before a concert and they had a quick sexual encounter before he was due on stage.

“It was making me very unhappy, I was disgusted with myself and terribly down,” she said.

But she still kept it a secret. “I was just so scared of him. (He was) a big man on telly, I thought no-one would believe me anyway. He was a huge character. I thought I didn’t stand a chance.”

She became a full-blown alcoholic, and said that makes it hard to fully recall some events in her 20s. But she says she began telling some people what was happening.

One night when she was drunk and living at home she told her parents.

Another time, when she was visiting Bindi and her partner, Bindi asked “why have you got a downer on my dad”.

“I didn’t say anything and she just blurted out ‘did he touch you?’,” the witness said. “So I looked at her and said ‘yes’."

“She was devastated but she wasn’t cross at me, she was really angry with her father.”

The relationship came to an end when she moved with her parents up to Norfolk in her late 20s, but she saw Harris one more time, she said.

“I was angry but confident I could deal with him, I felt I was strong enough to approach him.”

So she invited him up to visit her, and told him he had caused her misery, and she had always been scared of him.

“He was sorry for what he had done,” she said. “I said he had ruined my life. He said ‘oh God… I didn’t realise."

“He thought that we were friends. I said ‘I am not your friend’.”

She ‘paraded’ him round the town because she knew he didn’t like it, as a kind of revenge, and that was the last she saw of him.

She stopped drinking in 2000, but still gets panic and anxiety attacks, and is on medication for that. Her friendship with Bindi ended – “she just couldn’t cope”, the complainant said.

But in June 2012, when she saw Harris on the TV, “I just thought I can’t get away from this bloody man … I just burst out crying. It was like he was invading my home.”

Soon afterwards she decided to go to police with her claims, she said.

On Friday prosecutor Sasha Wass QC outlined the case against Harris.

She described him as a “Jekyll and Hyde” character whose talent and public generosity hid a darker side: he was sexually attracted to young women and girls.

“You will see a pattern during the course of this case of Mr Harris approaching girls in a purely friendly way and then, once he is in close physical contact with them, taking advantage of the situation in order to indecently assault them,” Ms Wass said.

Harris arrived at court on Monday hand in hand with his daughter and wife, Alwen. Alwen sat with a group of family and friends in court.

On Tuesday defence counsel Sonia Woodley will begin cross-examining the complainant.

The trial is expected to run until mid-June.