[2][5] From 1962 until 1993, Mayanja Nkanki served as the "Katikkiro" (prime minister) under Sir Edward Muteesa II, the Kabaka of Buganda, who reigned from 1939 until 1969.
In 1993, when the Kingdom of Buganda was re-instated, he was instrumental in the installation of the present monarch, Ronald Muwenda Mutebi II.
[2][5] In 1954, he was admitted to Keble College, Oxford on scholarship, graduating with a Master of Arts in politics, philosophy and economics in 1960.
On 17 August 1964, Nkangi, at age 33 years and a bachelor, was elected Buganda's katikkiro by the Lukiiko in a landslide.
In response, Obote ordered Idi Amin, the army commander at the time to attack the Kabaka's palace at Mengo.
[2][5][9] Also while there, he was able to witness the Kabaka's written desire to have his son Ronald Muwenda Mutebi succeed the Buganda throne, when that time came.
After Muteesa died on 21 November 1969, Mayanja Nkangi, in his capacity as Katikkiro, proclaimed the death, as is the custom.
[2][5][9] When the Obote II government (1980 - 1985) was overthrown by the military junta led by Tito Okello Lutwa, Nkangi was appointed minister of labour, serving in that capacity from August 1985 until January 1986.
Among the mourners were Uganda's vice president Edward Ssekandi, the Katikkiro of Buganda Charles Peter Mayiga, members of parliament and religious leaders.