 Independent operators Amber Lee, Carousel Buses, Imperial Buses, Redroute Buses and Sullivan Buses all provided vehicles made spare during the break in school terms; none had previously operated a Transport for London contracted route.Arriva London's tourist division The Original London Sightseeing Tour operated the route using closed-top MCW Metrobuses.After a month of service, First London and TfL subsidiary East Thames Buses joined the operation, while Stagecoach London operated additional journeys on route 53, which parallels the 185 over the southern section of route.