National Australian Archives Service records
JEFFREYS Leslie Gordon : Service Number - 6367 : Place of Birth - Sydney NSW : Place of Enlistment - Melbourne VIC : Next of Kin - (Wife) JEFFREYS Edith Isabel (digitised viewable on line)
JEFFREYS John Alfred : Service Number - 39110 : Place of Birth - Wentworth NSW : Place of Enlistment - Perth WA : Next of Kin - (Wife) JEFFREYS Amelia (digitised viewable on line)
JEFFREYS ROBERT STANLEY : Service Number - W48069 : Date of birth - 17 Aug 1886 : Place of birth - NEWCASTLE NSW : Place of enlistment - CLAREMONT WA : Next of Kin - JEFFREYS MYRTLE (not yet digitised but can request it to be)
If you search the Trove you will find a number of stories which relate to John Alfred Jeffreys husband of Amelia and his suicide in 1928 in WA.
Robert Stanley Jeffreys died in WA in 1962