It's a stab but looks like southern cross on the left side, VH -USU. The link below shows a photo collection from 1927/1928 of a flight around australia. There is a photo there at Essendon surrounded by a hoard of people but no tell tale buildings. Image 33 of 59.
National Museum of Australia - Mary Ulm's album
From Essendon airport web page /interactive timeline -"1933
Essendon Airport Welcomes aviation pioneer Sir Charles Kingsford-Smith
One of the largest crowds ever seen in Melbourne assembles at Essendon Airport to welcome aviation pioneer Sir Charles Kingsford-Smith (15th October, 1933)." It may not be his plane in the picture though.
The next pic is dated 1936 with a wider angle shot to the one above stating Ansett commences operations so it might be in the ball park?
http://www.essendonairport.com.au/general/our-history
Scroll down to interactive timeline and click the arrow on the right a few times.