Campaigners have called for urgent action to combat sexist abuse on the Tube amid fears that cases are not being thoroughly investigated.
Zan Moon received hundreds of responses after setting up a platform called Screengrab Them, which allows women to anonymously report harassment.
But she said she had been left disappointed that bystanders intervened in just one per cent of cases.
"Out of 200 responses, only two people had anyone intervene," she told the BBC, adding that "81 per cent had people around them who saw it happening, but chose not to do anything."
Ms Moon was inspired to set up the organisation after she was targeted by a man in his 40s on the Tube in January.
She reported her case to the British Transport Police (BTP) but it was thwarted as the CCTV footage was automatically deleted within 72 hours.
She has now called for the police and City Hall to take more action to combat sexist behaviour in public.
"It made me feel extremely unsafe," she said. "I felt violated.
"I called out for help multiple times and the carriage was full of men but nobody did anything to help so I had to leave the Tube, just for my safety and my partner’s safety.
"I was left just feeling horrified and uncomfortable in my own skin."
Despite reporting the crime the next day and giving a statement, Ms Moon said she "never really heard back" about what happened to her case.
Following meetings with the police, Ms Moon said is confident that the authorities are taking the matter “seriously”.
"There are just a few sticking points where we’re not seeing eye to eye, such as the CCTV, which I feel really strongly about," she said.
"We’re in 2022 and we can send a person to the moon and back, yet you’re telling me we can’t upgrade CCTV so it lasts longer than three days.
"That’s such a small window for victims to come forward and feel confident to talk about it, let alone report it."
A spokesperson for Sadiq Khan said the mayor believed "violence and harassment towards women" was a "deep cultural problem in our society", and preventative work was "an absolute priority".
They said: "The mayor is working with TfL and the police to stamp out this predatory behaviour and ensure a zero-tolerance approach to all forms of sexual harassment across the whole network."
Siwan Hayward, TfL’s policing director, said: "As well as proactive police patrols taking place across public transport, we work with the police to pursue all sexual harassment offences using our extensive network of CCTV and will be continuing to deliver sexual harassment training to all frontline staff."