I emailed the photos to the QLD Museum for identification.
http://www.qm.qld.gov.au/inquiry/identification.asp
An hour or so later they replied. Very quick service!!
Hi Jeanette,
The fly is called Amenia imperialis. It is common in eastern Qld and NSW and often selects obvious perching sites on rocks, fallen logs, tree trunks etc. The larvae are believed to be parasites of land snails and the adults feed on nectar.
Regards,
Steve Wilson
Inquiry Centre Information Officer
Queensland Museum
PO Box 3300
South Brisbane BC
Qld 4101
ph 07 38407640