After two years in the air force at the end of World War II, Halse left South Africa to study geology at Oxford University in England, gaining his Bachelor of Arts honors degree and a Master's degree.

He returned to South Africa and joined one of the world's leading mining group, the Anglo American Corporation, from where he was posted to the copper rich area of Zambia (then known as Northern Rhodesia). He spent 10 years there and in the adjacent territories of the Congo and central and east Africa in mineral exploration and mining. Ultimately, as chief geologist, he located and developed one of the first uranium deposits in the British Commonwealth and was involved in the development of certain major world copper mines in the area.

During this time he acquired membership in the British Institute of Mining and Metallurgy, later becoming a fellow of the organization. He is also a fellow of the Geological Society and a chartered engineer.

An interest in light aircraft flying, which still persists, enabled him to travel widely in Africa and Europe on both business and pleasure. On one occasion he circumnavigated Africa in a single-engine aircraft from the southernmost point of Africa to the northernmost point of Europe.

After becoming disenchanted with the apartheid regime of South Africa, where he campaigned actively on behalf of the new multiracial progressive party, he and his new family moved to Kenya in 1966. There he practiced for 30 years as an independent geological consultant in mineral, mining, and engineering geology. He is a resident of Cyprus, where he is still active in the consulting field.