Some newspaper mentions
http://www.rootschat.com/links/0xzj/Not helping with career highlights but perhaps you may be interested in this info
Which Wm was your person of interest....both father and son have the same names.
Death of Wm Snr
JOHNSON William Cowie
Father John Watts Mother Elizabeth LARVIE
At South Melbourne 70 years 1952 Reg#10821
JOHNSON William Cowie
Father William Cowie Mother Leah BITTON
Mother Leah BITTON
At Ferntree Gully 65 years 1974 Reg#313
Australian Electoral Roll
1914
JOHNSON William Cowie 99A Palmerston Crescent Albert Park Labourer
1931
JOHNSON William Cowie Jnr 233 York Street, South Melbourne Milk carter
JOHNSON William Cowie Snr 233 York Street, South Melbourne Labourer
1936
JOHNSON William Cowie Jnr 233 York Street, South Melbourne Driver
JOHNSON William Cowie Snr 233 York Street, South Melbourne Labourer
Wm Jnr occupation watersider from 1949 to....
1968
JOHNSON William Cowie 4 Queenstown Road Boronia Watersider
Wills and Probate Index
http://prov.vic.gov.au/index_search?searchid=54JOHNSON William C Pensioner Sth Melbourne 14 Aug 1952 456/132 VPRS 28/P4, unit 416
Cando