Bus conductor
（重定向自Clippie）
Until the 1970s and early 1980s, conductors, or clippies, were a common feature of many local bus services in larger towns and cities in the UK and Ireland. Conductors were portrayed in the British TV series On The Buses.
The main reason two-person crews were needed was that most towns and cities used double-decker buses for urban services. Until the 1960s, all double deck vehicles were built with front-mounted engines and a "half-cab" design, like the familiar Routemaster London bus. This layout totally separated the driver from the passenger saloons. The conductor communicated with the driver using a series of bell codes, such as two bells to start (the well-known "ding-ding").