Queensland State Archives posted a photo:
A float is a decorated platform, either built on a vehicle like a truck or towed behind one, which is a component of many festive parades.
Parade floats were first introduced in the Middle Ages when churches used pageant wagons as movable scenery for passion plays. Artisan guilds were responsible for building the pageant wagons for their specified craft.
The wagons were pulled throughout the town, most notable during Corpus Christi in which up to 48 wagons were used, one for each play in the Corpus Christi cycle.
They are so named because the first floats were decorated barges on the River Thames for the Lord Mayor’s Show.
Description source:
Wikipedia
View the original image at Queensland State Archives:
Digital Image ID 2985