Her brother, William Charles Wentworth IV (1907–2003), was a Liberal member for the Division of Mackellar in the House of Representatives, where he was a vociferous exponent of anti-communism, and of distinctive views on many other issues.
MacCallum was born in Sydney and educated at the elite Cranbrook School, a short walk from where he lived with his parents next door to his grandmother's house in Wentworth Street, Point Piper.
He continued to write political commentary, notably for the Australian Broadcasting Corporation (ABC) current affairs and news analysis program The Drum,[3] and for the magazine The Monthly.
He appeared on Australia's national Community Radio Network; and contributed columns for the Byron Shire Echo and The Northern Star, and cryptic crosswords for The Saturday Paper.
On 2 December 2020, MacCallum announced on the website "Pearls and Irritations" that, due to deteriorating health, he was finishing his journalistic career.