Bus conductors were the people who used to sell you your bus tickets.
They patrolled the double decks of the buses, printing tickets from portable machines slung over their shoulders, helped passengers on and off, and rang the bell to tell the driver — alone in his cab at the front of the bus — when it was safe to pull away from the bus stop. One ring for stop, two for go, and three for “Bus full up: Don’t stop at next stop.”
Once single-person-operated buses arrived, in the 1970s, the driver had to do the ticket selling and bus-pass policing as well as the actual driving.
Conductors had a brief resurgence in London when the new Routemaster bus, with its hop-on, hop-off platform at the back, arrived. Metroline, however, the bus operator recruiting them, advertised the position as that of “customer assistant”. They didn’t sell any tickets, after all, just “assist”.
By 2016, they were gone. Transport for London could no longer afford them.
I think it unlikely, in these days of Oyster cards, we’ll ever get them back.