Travelling on London's public transport system, you'll encounter the whole gamut of human behaviour. There's the positive and heartwarming: strangers giving up seats and helping women carry buggies up stairs, people leaving books for each other , and – sometimes – even having polite conversations . Then there's the other end of the spectrum: the angry commuters, intolerance , and intimidating violent and sexual behaviour, often directed towards women . Watching porn publicly on the bus or Tube most definitely falls into the latter category, and it's something many of us will have experienced. But this wildly inappropriate act could be about to become a whole lot less acceptable, as Transport for London warned that people who do it will be reported to the police. TfL has received a spate of reports of people watching porn on public transport, with most cases involving perpetrators watching it on their smartphones with headphones and turned away or attempting to hide their screen from others, the Evening Standard reported . It has urged passengers to report instances of public porn watching to members of staff, adding that they don't need to prove the incident was a criminal offence to do so. "We do not tolerate any unwanted sexual behaviour on our transport network," said Siwan Hayward, head of transport policing at TfL "We work closely with police taking all reports extremely seriously. If someone has made you feel uncomfortable, for example by viewing pornographic material, please tell the police or a member of our staff.” The issue has been a talking point in recent days. BBC Radio 4's Woman's Hour discussed it after one of the show's producers, Siobhann Tighe, witnessed a man watching porn on the bus during her evening commute. While she didn't confront the man, Tighe said it made her feel "uncomfortable and annoyed". And her experience is far from unique. One woman in her early thirties recalled her experience of seeing a man watching porn on the train who didn't think his fellow passengers could see. "It's a gobsmacking thing to do and makes everyone in the surrounding area extremely uncomfortable," she told Refinery29. "I would have moved but the train was so busy I was stuck in my spot and just bit my tongue. I welcome the new warning. It's crazy that men think it's ok to behave this way." Legally, watching porn in public is a grey area, with lawyers divided on the issue. Professor Clare McGlynn from Durham University, an expert in the law around porn, told Woman's Hour that the law would only prevent someone from watching porn in public if the person was harassing or disturbing others. However, James Turner QC tweeted the BBC to say that the the Indecent Displays (Control) Act could be used to prosecute a perpetrator.