Later the same year, the complainant told the police she had missed something out of her original statement, the prosecution said.
Arrangements were then made for the complainant to have an interview with police, which took place in 2023.
She said she had been playing a piece of music for the defendant and he asked whether he could do an experiment as she sounded in his words “strained”. He suggested that she leaned back on her heels while standing straight.
He approached her and said: “May I?”. She took this as him seeking permission to touch her hand, as he had done earlier in the consultation without incident, the prosecution said.
The complainant said she said yes but instead of him touching her hand, he put one hand on her waist and the other on her bottom, the jury was told.
The complainant was “shocked and not knowing how to respond” continued playing the violin. She said he put his hand over her crotch area, undid her trousers and sexually assaulted her with his finger.
Afterwards he asked how the experiment had felt and she replied “uncomfortable”, the prosecution said.
He then asked whether she noticed a difference and she said “not really”, the jury heard.
The interviewing officer asked why she had not given this full account the year before. She said she had told her mother only that he had touched her bottom because she was embarrassed – and that her mother had accompanied her to the police station, so she felt compelled to say the same to the officer, Ms Robinson said.
The defendant was arrested in 2023 at Gatwick Airport as he got off a flight.
The musician, from Walworth, south-east London, denies the charges.
The trial continues.