Bus Conductors. Until the 1970s & early 1980s, conductors, or clippies, were a common feature of many local bus services. Two-person crews were needed because until the 1960s, all double deck vehicles were built with front-mounted engines & a "half-cab" design. 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").
RMC1461 1962 AEC Routemaster coach London Bus Museum. These were originally on the Green Line routes, an express bus service. They used to wizz by, and the short fares were astronomical! 4s 6d for a journey that cost 6d on a red bus!