Hi Wallytat,
Not sure if this is your David Brown, but found these details on Australian War Memorial website:
David Brown
Rank: Lieutenant [Lt]
Unit: 41st Battalion (Infantry)
Service: Army
Conflict: 1914-1918
Date of death: 17 August 1918
Cause of death: Died of wounds
Cemetery or memorial details: FRANCE 148 St Sever Cemetery Rouen
War Grave Register notes: BROWN, Lt. David, M. C. 41st Bn. Australian Inf. Died of wounds 17th Aug., 1918. Son of William Edward and Mary Ann Brown, of 13, Kentville Avenue, Annandale, New South Wales. Native of Charters Towers, Queensland. Officers, B. 6. 27.
Source: AWM145 Roll of Honour cards, 1914-1918 War, Army