From A. Gibson. The Commonwealth. Young Learner Books. London: Chatto & Windus, 1965. Illustrated by David Harris.
From the Australian Government website:
"It is reported that in 1943 a flight of 24 RAAF Wirraways flew under the Sydney Harbour Bridge, with one of the pilots changing his flight path at the last moment to go over the top of the Bridge only just clearing it in time.
There is another story of the Americans flying under the Harbour Bridge, with one Kittyhawk flying under in about February 1942 and two Kittyhawks in May 1942. Again in May 1942, the Dutch flew three aircraft of the 18 Squadron NEI-AF under the Bridge in formation and then circled back to do another flight under the Bridge in a single line.
On 22 October 1943, Flight Lieutenant Peter Isaacson and his crew flew the huge Australian Lancaster, Q for Queenie, under the Harbour Bridge during a tour around Australia to raise funds for the war effort."
I can find only one photo of this last event:
As for Q for Queenie, she was eventually stripped for components, used for target practice, and then melted down into ingots.