This replica Avro 504K biplane is on public display at Sydney's Mascot airport. It was built in 1988 by QANTAS as a flying replica of the first aircraft they began services with in February 1921, G-AUGB. They apparently built two of these replicas. One is shown here, and this one has an original Dyak engine, and the other is in the QANTAS Founders Museum at Longreach in Queensland.
The original G-AUGB was powered by a 6-cylinder inline water cooled Sunbeam Dyak engine in place of the usual rotary Gnome or Clerget powerplant. It was assembled locally by the Australian Aircraft and Engineering Co.
Many thanks to Mark Pilkington for clearing up the identity of this machine.