I see he was born in Osgathorpe, registered Ashby de la Zouch
He married in 1911
No sign in the passenger lists as far as I can tell
There is a marriage in Perth in 1930 for a John SIDDONS but can't work out how to find the spouse
On the National Archives of Australia, there are two items of interest, an Edith (John) SIDDONS 1933
B741 V/11309 Mrs Edith (John) Siddons
Access status: Open
Location: Melbourne
1933 - 1933 405196
and a John SIDDONS
B884 V144583 SIDDONS JOHN : Service Number - V144583 : Date of birth - 18 Aug 1880 : Place of birth - LEICESTER ENGLAND : Place of enlistment - ROYAL PARK VIC : Next of Kin - SIDDONS EDITH
Access status: Not yet examined
Location: Canberra
1939 - 1948 6275283
I suspect you have most or all of the following
Interesting that he lived on Cobden street as there is one in Leicester as well
Marriages Dec 1911
Siddons John Leicester 7a 600
Taylor Agnes M Leicester 7a 600
Electoral rolls
1931
Kew Kooyong Victoria
SIDDONS John 22 Cobden street labourer
SIDDONS Edith 22 Cobden street home duties
1937 & 1939 as above
1949
Joan Mary clerk
Edith home duties
John labourer
All SIDDONS 22 Cobden st
1954
John
Edith
All SIDDONS 22 Cobden st
1963
John nil
Edith home duties
No2 70 Childers st
1968 & 1972
Edith
No2 70 Childers st
My attention was drawn to your post as first I was born in Leicestershire (about 15 miles from Osgathorpe) and second my wifes side also of Leicestershire but Derbyshire as well, are sometimes recorded as SIDDONS, their main name is SITDOWN or SIDDOWN