Tribe joined the University of Queensland's Faculty of Medicine (where he edited the University medical society's journal Trephine), but found that he did not enjoy hospital work and left. It was not long after this that he left Australia for Britain, where he worked at various times as a sketch artist, public relations officer, journalist and lecturer.
In Britain, Tribe was chair of Humanist Group Action (1961-1964), President of the National Secular Society (1963–1971), editor of The Freethinker (1966–1967). He was also an executive committee member of the National Council for Civil Liberties (1961–1972).
Since returning to Australia, he has continued to work for the secularist and humanist movement, but has not held office in any organisation.
In 2001, Tribe became an honorary associate of Rationalist International.
- The Rise of the Mediocracy (1975). London: Allen & Unwin. ISBN 0-04-300057-6
- Questions of Censorship (1973). London: Allen & Unwin. ISBN 0-04-701007-X
- Broadcasting, Brainwashing, Conditioning (1972). London: National Secular Society. ISBN 0-903752-01-8
- Nucleoethics: Ethics in Modern Society (1972). London: MacGibbon and Kee. ISBN 0-261-63266-3
- President Charles Bradlaugh, MP (1971). London: Elek Books. ISBN 0-236-17726-5
- The Cost of Church Schools (1970). London: National Secular Society.
- Humanism, Christianity, and Sex (1968). London: National Secular Society.
- 100 Years of Freethought (1967). London: Elek Books.
- Why are We Here? (a poem) (1965). London: Outposts Publications.
- Religion and Ethics in Schools (1965). London: National Secular Society.
- Freethought and Humanism in Shakespeare (1964). London: Pioneer Press.