From all accounts the Wirraway stalled in a low level steep turn with insufficient height to recover.. From personal experience of those days, the Wirraway had violent stalling characteristics in a power on steep turn and would sometimes flick inverted. It was called a high speed stall and all Wirraway pilots would have experienced this in their training on Wirraways.
A known issue with Wirraway's, and the pilot notes include cautions regarding the tendency to drop the left wing during the flare.
I too wonder whether it is worthwhile trying to solve such a mystery after such a long period of time.