She claims she was deliberately excluded from a company dinner with one of her clients, the tech firm Flipboard, held at the San Francisco apartment of Al Gore, the former vice-president, who happened to live in her building. When she bumped into Flipboard's chief executive, with whom she had been working closely, she had to tell him she would not be seeing him up there as she had not been invited. "It was more than humiliating," her counsel told the city's Superior Court jury on Tuesday. She says she was later told by a senior partner at the company, which was an early investor in Google, Amazon and AOL, that women were not invited because they "kill the buzz". Cases such as that of Ms Pao rarely make it to trial in Silicon Valley, which was founded on a model of West Coast hippy capitalism that presumes to have moved on from old-fashioned sexist attitudes.

Women who have complained over the years have generally been silenced with confidentiality clauses or generous out-of-court settlements, depending on the seriousness of the allegations. "Silicon Valley's dirty laundry is on full view," Deborah Rhode, a Stanford University law professor who teaches gender equity law, told The Sunday Telegraph. "It's a much-needed wake-up call for the industry, which is almost as bad for its misogyny as the Wall Street of the 1980s." She said the combination of the traditional old boys' network of wealthy investors and the tech companies being run like fraternity houses by their young male chief executives had created a uniquely toxic environment for women. Last year, a group of women, working at companies including Adobe and Mozilla, wrote an open letter addressed "to the tech industry". "Some of us identified as feminists before we came to this industry," it read. "Some of us only began to understand the relevance of feminism as we sought to understand what's been happening to us. We are tired of pretending this stuff doesn't happen." Some took their complaints further.

Whitney Wolfe, former marketing vice-president at the dating app Tinder, sued the firm in July of last year, alleging that she was called a "whore" in emails sent by Justin Mateen, a marketing executive, and was stripped of her co-founder title and demeaned because she's "a girl". Mr Mateen reportedly said that having a 24-year-old woman co-founder "made the company seem like a joke". As a result, he was suspended, the chief executive also stepped down, and the company quietly awarded Miss Wolfe $US1million in a settlement. Just a few months later, Rachel Kremer, 30, who worked in sales at the property website Zillow, filed a lawsuit, saying it operated like an "adult frat house". She said male supervisors "ranked her according to her breast size, sent pictures of their penises to her, and demanded sexual gratification and obedience". Miss Taylor bemoaned the lack of role models for women in tech. She noted that those who did make it to the top, such as Sheryl Sandberg, the Facebook chief executive, and Marissa Mayer, the president of Yahoo!, kept tight-lipped about any similar experience they might have had.

Last year, several of the bigger Silicon Valley companies released a breakdown of their workforce for the first time. They revealed that at Google, only 17 per cent of the engineers were female, while at Facebook they made up just 15 per cent. They were losing ground in venture capital leadership, with only 6 per cent of partners female, down from 10 per cent in 1999. Taking the stand this week in Ms Pao's defence was Trae Vassallo, another former junior investor, who described the often "predatory" behaviour in the office. She said that Mr Nazre had once put his hand on her leg during a business meeting. Mrs Vassallo, a married mother, also testified that he had flown her to New York under the pretence of meeting an important tech client. Later that evening, she said, Mr Nazre tried twice to enter her hotel room wearing only a dressing gown and slippers.

When she told her boss on their return, he said she should be flattered, and wrote it off as a humorous misunderstanding. It was revealed in court that Mr Nazre was fired by Kleiner Perkins after an investigation into sex harassment claims. He has not made any public comment on the allegations. Kleiner Perkins has denied all the allegations, saying Ms Pao, who was fired in 2012, did not receive a promotion as she "didn't even come close to having the necessary skills for the job". While Kleiner Perkins boasts more female employees than many of its competitors, only one woman has made managing partner in the company's 40-year history. Figures suggest the lack of women in Valley firms is becoming more pronounced. A 2014 Harvard Business Review study described an "exodus" of women from the engineering and technology industries. "Sooner or later this has got to be addressed, otherwise these companies will find themselves in real trouble," said Professor Rhode. "Whatever the outcome of this case, the problem is no longer an open secret."

Telegraph, London