Soldier, member of parliament, and diplomat. Gullett was one of the handful of Australian officers at the Normandy landings. The son of Sir Henry Gullett, one of the Australian official historians of the First World War, 'Jo' Gullett was a Melbourne journalist when he enlisted in the AIF in 1939. Educated at Oxford and the Sorbonne, he had inherited an old fashioned sense of honour and duty. 'We knew England's position was very serious and that we should help her as our fathers had done. It was the order of things.'

When Australian troops first went into action at Bardia, Libya, in January 1941, Gullett was there as an infantry sergeant. He was wounded in the taking of Post 11, which the Italians had stoutly defended, but rejoined his battalion in time to serve as an officer in the ill-fated Greek campaign. He later fought in New Guinea and was awarded the Military Cross for his "disregard of danger and [for] leadership".

In 1944 Gullett was one of the few Australian soldiers sent to Europe to take part in the British D-Day operations. He was able to get an appointment with an infantry battalion. Soon afterwards he was made a company commander with The Royal Scots, and served with them during the further fighting until again wounded on 17 July. A staff job awaited him on his return to Australia.

While others may have seen boredom and disruption in war service, Gullett found some "colour, music and a touch of glory in that life". His account of his experiences, Not as duty only (1976) is a classic of Australian war literature. His part in the fighting at Bardia is depicted in Ivor Hele's famous painting, 2/6th Battalion Attack on Post 11 at Bardia.

Gullett followed in his father's footsteps when he entered parliament in 1946; he was elected the Member for Henty. He became the Chief Government Whip (1950-55) in the Menzies' Liberal Government. He was Australian Ambassador to Greece (1965-68), before returning to farming at "Lambrigg" property, Tharwa, in the Australian Captial Territory.