I found the following: The Sydney Morning Herald, March 12th 2001, p. 37

"In 1955 the Wattle recording company issued its first disc, the Bushwackers singing The Drover's Dream. The first Australian folk "hit", it sold more than 20,000 copies."

I didn't find anything from the 1950s explicity stating that, but it looks like it was first released on a 33 rpm album titled "Australian Folk Songs" by The Bushwackers rather than Alan Scott on his own