What was the controversy about Brett Whiteley winning the Archibald prize in 1976?

The controversy surrounding Brett Whiteley's win of the Archibald prize in 1976 stemmed from accusations that his painting, "Self Portrait in the Studio," contained elements that were not painted by the artist himself, specifically the background. Some claimed that the painting violated the rules of the competition. However, Whiteley defended his work, stating that the background was necessary to convey the artist's environment and process. Ultimately, Whiteley was allowed to keep the prize.