[1] His father was killed in World War II while fighting on the New Guinea campaign and he was raised on his grandfather's farm near Seymour, Victoria.
[1] In parliament, Mackenzie serving on the Standing Committee on Environment and Conservation from 1980 to 1983 and was made a deputy whip for the National Party in 1981.
[1] After leaving parliament, Mackenzie was executive director of the Geelong Grammar Foundation from 1984 to 1995.
[3] He was later active in conservation circles as an advocate for "restoration of the lower Darling River, sustainable farming and community empowerment in public environmental and agricultural policy".
[6] He served on the Victorian advisory council for Landcare Australia and represented the organisation at the National Drought Summit in 2018.