Upon graduation, Potter moved to Melbourne to take on a position as economist with stockbroker Edward Dyason, a successful mining entrepreneur and trained economist. In 1933, Potter began an eighteen-month period as a Treasury economist in Canberra providing him with an intimate knowledge of government finance. He also made many contacts in politics and the federal bureaucracy. Upon his return to Melbourne in 1935, Potter established his own stockbroking firm, W.I. Potter, and then from 1937, Ian Potter & Co.
World War II Potter continued his business interests during the war while training for, and serving in, the
Naval Auxiliary Patrol (NAP). Like many small motor vessel owners, Potter volunteered his own boat, the MV
Nordecia, to the NAP.
Nordecia was later commissioned as HMAS
Nordecia, carrying the bow number 624.
Nordecia was fitted with a machine gun and depth charges. Enlisting on 17 August 1942, Potter trained as a Royal Australian Navy Volunteer Reserve (RANVR) cadet. He was commissioned as a Staff Skipper with substantive rank of Sub Lieutenant on 8 May 1944, and stationed at
HMAS Lonsdale, Port Melbourne, until his discharge on 31 May 1946. Following the war, the members of the NAP established the Little Ship Club to maintain the skills acquired during their service. In 1949,
King George VI approved warrants for the award by the
Royal Navy of the
Blue Ensign (Defaced) to the Little Ship Club, and to Potter's HMAS
Nordecia as well as the
San Vittoria and
Mauranne, for service during the war. This is the only award of the Blue Ensign (Defaced) to an Australian boat club for wartime service. The Blue Ensign (Defaced) included a light blue coloured circle representing the dawn, within which a five-pointed star represents the guiding star of their overnight patrols around Port Philip Bay. ==Other roles==