Whetstone served as the Minister for Primary Industries and Regional Development in the Marshall Ministry from 22 March 2018.

He finished a tool maker apprenticeship at General Motors Holden and then went on to develop his own business building and restoring muscle cars and boats.

[3] Whestone was a project manager on the Moomba gas fields before moving to the Riverland in 1989 to purchase a citrus property and develop a vineyard on the River Murray.

[4] The SA Nationals did not contest the 2014 election, which saw Whetstone win 75.1 percent of the two-party vote.

[6] In July 2020, Whetstone admitted to wrongly claiming travel expenses on 90 occasions, including several claims for accommodation in Adelaide at the same time as he was undertaking international or interstate travel, in what Premier Steven Marshall described as "extraordinarily disappointing" behaviour.