Queensland State Archives posted a photo:
Firemen’s Arch Of Ladders
The Metropolitan Fire Brigade intends to take part in the welcome to the Duke and Duchess, and it is planned that with their equipment the men shall form a novel arch under which the Royal procession will pass. This will be carried out with the ladders, which, mounted on their trollies, will be extended to form the two wings of the arch of welcome. With the firemen at their posts on the vehicles, this will form an effective picture, which should be all the more striking because of its novel formation.
Description source:
The Telegraph, 5 April 1927
View the original image at the Queensland State Archives:
Digital Image ID 18211