Project Guardian is a joint initiative between British Transport Police (BTP), the Metropolitan Police Service ("the Met"), the City of London Police, and Transport for London (TfL), which aims to combat and increase reporting of sexual harassment on public transport in London. The initiative was inspired by a similar operation in Boston, Massachusetts, and began after a TfL survey revealed that 15% of women who used London's public transport had experienced some form of unwanted sexual behaviour, but that the overwhelming majority of incidents were not reported to the police. Project Guardian aimed to increase reporting and reduce instances of such behaviour.
As part of the project, the police created a confidential hotline and text-messaging service and used social media to raise awareness and encourage reporting. They also staged several "weeks of action", involving increased patrolling of public transport by both uniformed and plain-clothed police officers, including a joint initiative with police officers in several cities in North America, several of which resulted in multiple arrests. In August 2014, the BTP recorded a 21% increase in sex offences, a rise which was attributed partially to increased reporting as result of Project Guardian.