The Knight Bus is a triple-decker, purple AEC Regent III RT that assists stranded individuals of the wizarding community through public transportation. It operates at a very fast speed and obstacles will jump out of its way, and can also deceptively fit through small spaces. To hail the bus, a witch or wizard must stick their wand hand in the air in the same manner that a Muggle might do while hailing a Muggle Bus in the United Kingdom, though it is possible to book tickets for travel on the bus in advance.
The Knight Bus is a relatively modern invention in wizarding society, which sometimes (though it will rarely admit it) takes ideas from the Muggle world. The need for some form of transportation that could be used safely and discreetly by the underage or the infirm had been felt for a while and many suggestions had been made (sidecars on taxi-style broomsticks, carrying baskets slung under Thestrals) all of them vetoed by the Ministry. Finally the Knight Bus was first commissioned in 1865.The idea was proposed by then-Minister Dugald McPhail.
While some wizards (mainly pure-blood fanatics) announced their intention of boycotting what was dubbed ‘this Muggle-esque outrage’ in the letters page of the Daily Prophet, the Knight Bus proved hugely popular with most of the community and remains busy to this day.
During the early 1990s, the Knight Bus' conductor was Stan Shunpike, who greets passengers and handles baggage, and was driven by Ernie Prang.
The Leaky Cauldron offered tickets for the Knight Bus as part of its room service.
When searching for the cache, you could pretend you are waiting for the Muggle Bus ...