If only his brothers Vincent and Austin were as easy to find!
Reenie 
Is this his brother Austin?

Austin Hardy (died 1954 age 75 years Melbourne)
Father: William John Mother: Sarah Jane Rudge
married
Hilda M Douglas in Perth 1908 (died 1972 age 87 years Carn)
Father: Lancel Douglas Mother: Mary Jane Wynne
Electoral rolls
1916 - Unit Street, Wagin, Western Australia
Austin Hardy – Accountant
Hilda Mary Hardy – married
1925 - 89 Hill Street, Perth,Western Australia
Austin Hardy – Acountant
Hilda Mary Hardy – Home duties
William John – Engraver
1931 and 1936 - 409 Clarendon Street,South Melbourne,Victoria
Austin Hardy – Accountant
Hilda May Hardy – Home Duties
and his brother Vincent?

Vincent Rudge Hardy (died 1960 age 78 years Chelt)
Father: William John Mother: Sarah Jane Rudge
Can’t see a marriage in Victoria for Vincent
Electoral Rolls
1916 - 137 Wellington Street, Perth,Western Australia
Basil Joseph Hardy – Clerk
Sarah Jane Hardy – Married
Vincent Rudge Hardy – Clerk
William John Hardy – Engraver
1931 - 39 High Street, Prahran,Victoria
Vincent Hardy – No occupation listed
1936 - 9 Grattan Street, Prahran, Victoria
Vincent Rudge Hardy - Clerk
Both Vincent and Austin are listed on
http://www.naa.gov.au/Series No MT1486/1 which is Applications to enlist in Australian Imperial Force
Raylen