Busch was born in an inner suburb of Brisbane, Queensland, on 26 October 1920. His father was a German migrant pork butcher, his mother Harriet had been born in Queensland. Busch grew up in Toowoomba, and got a job as a telegram boy at age 15 to help support the family during the Great Depression. His immediate family remained in Toowoomba for the rest of their lives.
Busch lectured Philosophy at University of Queensland whilst also studying as an external student at Melbourne College of Divinity then at the Presbyterian Theological Hall within Emmanuel College at UQ. He was ordained on 16 February 1954. He also spent a year studying at Union Theological Seminary, New York in 1958. Busch was professor of New Testament studies in the Presbyterian Theological Hall from 1961 and in the Congregational, Methodist and Presbyterian Joint Faculty of Theology from 1968. He was also principal of Emmanuel College from 1962 to 1978. He convened the Queensland Presbyterian department of Christian education from 1960 to 1963 and the board of local mission from 1970 to 1974. His qualifications included: ;University of Queensland ;Melbourne College of Divinity ;Columbia University
Ministry
When he was ordained, Busch was inducted into pastoral charge of St Giles's church at Yeerongpilly in Brisbane. He was state moderator of the Presbyterian church in 1972-3 and after union of the Queensland Synod of the Uniting Church 1977–1979. He was President of the National Assembly of the Uniting Church for a three-year term from 1982. He served as chairman of the Brisbane College of Theology in 1985.
Awards, honours and titles
Professor of Theological Studies at University of Queensland in 1961
President of the Assembly of the Uniting Church in Australia from 1982 to 1985.
Aboriginal Rights
Busch was a firm believer in Aboriginal Rights and in the right of self-determination for many Aboriginal settlements. His criticism was voiced against the Queensland government's denial of self-determination to the Aboriginal inhabitants of Aumkun and Mornington Island , pitting him against Sir Joh Bjelke-Petersen on several occasions. The Uniting Church has continued their support of Aboriginal Rights in Australia.
Family
On 14 August 1948 at St John's Church of England, Penshurst, Sydney, he married Evelyn Mavis Smith, a nurse whom he had met in New Guinea during the war. They had two children. Both Ian and Rhonda's Husband have served on the boards of the UCA Queensland Synod and Wesley Hospital.