Geoff received an MA (UCT, 1961) and a PhD (University of Sheffield, UK, 1982) for research into four South African writers, Pauline Smith (MA), Roy Campbell, William Plomer and Laurens van der Post (PhD). His work on Smith became a pioneering study published in Twayne World Authors Series (New York 1969). Geoff taught first at Rhodes University (1961) then at Wits (1963–1968). He returned to UCT in 1969 as a Senior Lecturer in English Literature, remaining there until his retirement in 2005 with the title of Emeritus Professor. 

Geoff has published creative writing and literary criticism throughout his career.  He has five collections of poetry to date: Drive of the Tide (Maskew Miller, 1976), New-Born Images (Justified Press, 1999), Mulberries in Autumn (Snailpress 1996) The Living and the Dead (Snailpress, 1996) and Where the Wind Wills (Echoing Green Press 2011). Snailpress published his Selected Poems in 1996. His novel Testimony (Justified Press, 1992) received a Heinemann/Weekly Mail award, and parts of African Tales from Shakespeare (Juta-Gariep, 1999) were anthologized. He has published numerous literary essays in journals and collections such as Race and Literature (Owen Burgess, 1987) Perspectives on South African Writing (Ad Donker, 1992) and Conrad in Africa (Columbia University Press, 2002). In 2017 he received a Thomas Pringle Award from the English Academy of Southern Africa for Ad hoc Reviews and Review articles.

Editorial work has occupied him for over sixty years. It began in the 1950s by editing at UCT the student literary magazine, Groote Schuur, which published the early work of J. M. Coetzee, C. J. (Jonty) Driver, Stephen Gray, Breyten Breytenbach and Adam Small. From 1980 to 1989, he was editor of Contrast, South Africa’s leading literary magazine. Over the past several years he has been a Creative Writing editor for the English Academy Review. Individual titles which he has edited are The Great Hunters (Purnell, 1974), William Plomer: the South African Autobiography and Plomer’s scathing biography, Cecil Rhodes (both David Philip, 1984).

With UCT remaining his ‘home port’, Geoff has spent sabbatical years and/or special leave researching in Rhodes House Library, Oxford University (1972), the University of Sheffield (1979), and Clare Hall, Cambridge University (1984). He was later named a Life Member of Clare Hall which keeps a collection of his publications in the college library. In the 1990s he was twice a Visiting Professor of English at Dalhousie University, Canada’s oldest tertiary institution. The University of the Western Cape appointed him as an Extraordinary Professor of English from 2006 to 2008. He is currently Honorary Vice President of the English Academy of Southern Africa and a former Vice President and Honorary Member of the South African PEN Centre. Currently he enjoys belonging to the Cape Town Branch of the Shakespeare Society of Southern Africa. Very little that he has achieved could have been done without the love and support of his wife, Lesley Deeble. They first met as UCT undergraduates in 1957.