Looking at siblings there is a marriage for a Norman A Brown [birth on NSW BDM] 1928 to a Dorothy Elizabeth Sleath.
A couple of public trees point to this..
Sydney, Australia, Anglican Parish Registers, 1814-2011:
Norman Arthur Brown
Marriage Age: 22
Birth Date: abt 1906
Marriage Date: 5 Apr 1928
Marriage Place: Sydney, NSW
Parish as it Appears: CLEVELAND ST
Father: Andrew Fowtes Brown*
Mother: Eliza Brown
Spouse: Doris Elizabeth Sleath
[*farmer]
Geoff