[4][5] Shaun Matthews was on vacation at the Grange and reported seeing an object with a slight purple hue and about twice the size of a family car.

The Weather Bureau released a balloon at Laverton at 8:30 am and the westerly wind blowing at the time could have moved it into the area where the sighting was reported".

Basterfield located documents in the National Archives and former Department of Supply indicating a test balloon launched from Mildura may have been blown off course "and came down in Clayton South in a paddock near Westall High School, alarming and baffling hundreds of eyewitnesses, including teachers and students".

Basterfield said HIBAL balloons had a white silver appearance and featured a parachute and gas tube trailing from the top, which is consistent with witness descriptions of the object.

Dunning suggested a nylon target drogue, like a wind sock, towed by one plane for the others to chase and known to be in use by the local RAAF at the time, was "at least one very reasonable possibility for the second half".

[10][11] The Phenomenon, a documentary film directed and co-produced by ufologist James Fox, includes content related to the Westall UFO case.