He purchased Benara station, near Mount Gambier, around 1874 and sold it to Captain R. Gardiner six years later at a substantial profit.
[1] He was elected to the House of Assembly seat of Victoria made vacant by the resignation of George Charles Hawker in June 1883.
In 1883, he and W. McEllister embarked on an ambitious speculation in the wheat market.
Anticipating cornering the market, they purchased 5000 bales of wheat bags and chartered 20 or 30 clipper ships to carry the harvest to Europe[3] and employed 44 inspectors to assess the qualifying farms.
[4] With the death of his brother Robert in 1884, William Whinham assumed management of the North Adelaide Grammar School, but after a few years returned to his business interests.