As a kid in Nottingham in the late 1950s and early 1960s, I used to love the trolleybuses - green 6-wheelers made by Metro Cammell. They were much bigger, quicker, smoother, quieter and cleaner than the diesels, and had additional stops. However, I also remember traffic jams caused by the occasional "dewirement" incidents - the "points" at junctions were particularly troublesome. It was highly amusing watching the driver and conductor trying to snare errant trolley poles that were pointing skywards, using the long hooked pole that the bus carried for this purpose!
The reach of the trolley poles enabled the bus to manoeuvre around road works and other obstructions, and if one bus failed its trolley poles were quickly stowed to let others overtake - much more resilient than street-running trams, where one obstruction or failure can bring the whole system to a halt. They were even able to crawl short distances on battery power when necessary. At one time there was a trolleybus route all the way from Nottingham to Ripley via Ilkeston and Heanor, some 15 miles, although this was closed when I was very young.
Nottingham City Transport's argument for scrapping the trolleybuses, in the face of popular opposition, was the high and increasing labour cost of maintaining the wires and, especially, of rerouting them as the city centre was redeveloped and the roads improved. In contrast, diesel was dirt cheap at that time. Most of the network was already diesel, because the wires were never extended into the post-war housing estates. The replacements were "modern" rear-engined diesel buses (Leyland Atlanteans), which were claimed to match the trolleybuses for capacity, acceleration, noise and cleanliness (which, of course, they didn't, even when new).