The technology has been fitted as part of the mayor of London’s pledge to improve safety for women and girls, external, TfL said.

Siwan Hayward, TfL’s director of security, policing and enforcement, said it was “one of many measures” being put in place.

“We want women and girls to be safe and feel safe, and for the TfL network to be a beacon of safety for everyone, day and night.”

Michael Roberts, chief executive officer of London TravelWatch, said the group’s research found many women and girls felt unsafe waiting for buses.

“This important and valuable trial will not only help detect crime, but will also ensure that women and girls can feel safer and more confident when travelling by bus,” Ms Roberts said.