Menangle Park Racecourse was opened in 1914. After the outbreak of World War I it was requisitioned as an army camp to be used for the Australian Light Horse. Post-war it was returned to the owners for horse racing, until 18 November 1941, when again the racecourse was taken over by the military during World War II.
The Menangle racecourse was duly converted into a military camp, providing camping and training facilities for Royal Australian Air Force. The RAAF constructed an aerodrome at the site in 1942, right through the middle of the racecourse. The strip was most likely a dispersal strip for (nearby, to the north and west) RAAF Camden; however records also show it as a satellite aerodrome for RAAF Station Schofields. The runway was (as almost always) 5,000 feet (1,500 m) long and 150 feet (46 m) wide. 7 splinterproof pens and 5 concealed hideouts were constructed. The site was also used as an aircraft overflow, a parking area for HMS Nabthorpe, a Royal Navy Mobile Operational Naval Air Base, again based at Schofields.
Given the restrictive locations of both the river and the railway, the runway had to run roughly north-south through the middle of the racecourse. (Google Maps image.)
This National Archive image (NAA Menangle Park 1942-51 CRS NAA SP 85/76 PH/599) illustrates that runway location. Not shown are the dispersal "hides".
The name "Menangle" derives from an Aboriginal word, in English spelt either as Manhangle or Manangle. This word was used by the Tharawal people to describe either a small lagoon on the opposite side of the Nepean River or 'a place of swamps' generally. It was from that lagoon, on the west bank, that in 1805 a 2000 acre (800ha) grant was awarded to Walter Davidson. He called his new farm Manangle, after that same lagoon.
The nearby Menangle Viaduct is the oldest surviving rail bridge in New South Wales. Stone for the viaduct was quarried (c. mid to late 1850s) from the property of Thomas Vardy. A temporary tramway carried the stone to the work site. Workers were accommodated nearby in "canvas huts".
Interestingly, a Mary Reiby owned a parcel of land in the Menangle Parish (Parish map, below). Without checking further I'm assuming that's Enmore's Mary Reiby. Some fact-checking required here!
More at Wikipedia, Wollondilly Council (1) and (2); and Campbelltown City Council (1)
My list of Sydney's race tracks and circuits.or checkout my list of Sydney and surrounding airstrips and airports.