Born in Hereford, Kay was the eldest of six children. Her father, Harry, was the founder of Wyevale Nurseries, which was to become one of the largest garden centre chains in Europe. She was educated at Hereford girls' high school and St Hilda's College, Oxford, where she took a BA in English in 1956, followed by an MA in 1960.
Her romance with Africa began with her visit in 1956 to the then University College, Ibadan (now the University of Ibadan) in Nigeria, when she was given a Leverhulme scholarship to undertake postgraduate study. After a brief stint as assistant lecturer (1957-59) at Yale University, in 1964 she received her PhD in linguistics on the submission of a thesis on the grammar of the Kolokuma dialect of Ijo. It was one of the first attempts to apply Noam Chomsky's transformational theory of grammar to the description of a non-European language.
Kay returned to the University of Ibadan in 1963 as lecturer in linguistics, and became professor in 1972. She was appointed head of department in 1975. A key figure, responsible for establishing linguistics as a discipline at the university, she had a way of bringing out the best in students and explaining difficult concepts in a simplified and lucid manner.
When she moved to the University of Port Harcourt in 1977, Kay continued her leadership role in teaching and research until her retirement in 2000; the university then continued to benefit from her scholarship when she was appointed to the Unesco chair in cultural heritage.
When the time came to write a book devoted exclusively to the classification and description of Niger-Congo languages, Kay was the obvious choice for the general overview. Published in 1989, this 43-page article has become a classic in the comparative historical study of African languages.
Kay was not only a researcher, but also a prolific writer. Her list of publications includes more than 12 books and monographs, and almost 70 articles. Although she came to linguistic research with the best theoretical training one could have, her main interest was to describe language and language relationships in a usable manner, rather than as a purely academic exercise intended for the consumption of linguists.
In this concern for social responsibility in linguistics, she devoted a substantial part of her time to the Rivers Readers Project, an exercise designed to introduce reading and writing in primary schools in about 20 dialects or languages in the predominantly Ijo-speaking area. As a byproduct, several books (including primers, readers, teachers' notes, spelling manuals, and collection of folk-tales) were compiled by Kay and her collaborators.
It did not bother her that such works do not earn plaudits as academic publications. She was totally convinced that a linguist must help speakers of the languages of her research to produce texts in their languages. That was why she encouraged several of her Ijo collaborators to become experts in their languages.
In the community of linguists, Kay was highly respected. She was a formidable presence at the biennial congresses of the West African Linguistic Society, hardly missing a meeting since its founding in 1965 and always presenting a paper. Her opinions on linguistic matters were eagerly sought, and her comments on any presentation were always taken seriously.
Internationally, she was well-known and had been invited to positions in Europe and America; but, out of choice, she decided to remain in Nigeria, only going abroad for conferences or sabbaticals, as, in 1984-85, when she was visiting scholar at Leiden University in Holland, and, in 1991-92, when she was at Wolfson College, Oxford.
Kay loved Nigeria and would probably have wished to remain there, but for the heart condition which took her back to England. She was kindhearted, easy-going and a model of simplicity; from a Methodist background, she had become a Quaker. Her home on the campus of the University of Port Harcourt was always open to all, and her library treated by her students as an unlicensed public facility.
She is survived by her two sisters and two brothers.
· Ruth Margaret (Kay) Williamson, linguist, born January 26 1935; died January 3 2005
