Graduated in English from University College, London (BA, PhD), worked on the Survey of English Usage, then joined the Linguistics Department in Bangor (1963-5). Lecturer, Reader, and Professor of Linguistics at the University of Read ing (1965-85), then Honorary Professor of Linguistics at Bangor.
Now works from his home in Holyhead as a writer, lecturer and broadcaster on language and linguistics, and as editor of the Penguin 'family' on general encyclopaedias.
A former editor of several linguistics journals and series, his research interests have included Shakespeare's language, linguistic diversity, and the application of linguistics in internet contexts. Recent publications include the second editions of The Cambridge Encyclopedia of English Language, The Language Revolution, The Stories of English, and Pronouncing Shakespeare.