I had the amazing opportunity to sit at the console of the Sydney Opera House organ, very recently, during a visit to Sydney. Many thanks to Murray for taking the time to show me around and to my friends, Callum and David for an enjoyable day of organs, music and food! The Grand Organ was built during the period of 1969 to 1979 by Ronald Sharp, assisted by Mark Fisher, Myk Fairhurst and Raymond Bridge (his personal staff). It is believed to be the largest mechanical organ in the world.
Organ specification: https://www.ohta.org.au/confs/Sydney/GRANDORGAN.html
See all the organs in Australia here: https://australianorgans.com.au