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. 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 to hail a taxi, though it is possible to book tickets for travel on the bus in advance.
The AEC Regent III RT was a variant of the AEC Regent III. It was a double-decker bus produced jointly between AEC and London Transport. It was the standard red London bus during the 1950s.