David works from his home in Holyhead, North Wales, as a writer, editor, lecturer, and broadcaster. Born in Lisburn, Northern Ireland in 1941, he spent his early years in Holyhead. His family moved to Liverpool in 1951, and he received his secondary schooling at St Mary’s College. He read English at University College London (1959-62), specialised in English language studies, did some research there at the Survey of English Usage under Randolph Quirk (1962-3), then joined academic life as a lecturer in linguistics, first at Bangor (1963-5), then at Reading (1965-84). He published the first of his 100+ books in 1964, and became known chiefly for his research work in English language studies, in such fields as intonation and stylistics, and in the application of linguistics to religious, educational and clinical contexts, notably in the development of a range of linguistic profiling techniques for diagnostic and therapeutic purposes. He held a chair at the University of Reading for 10 years, and is now Honorary Professor of Linguistics at the University of Bangor.

His authored works are mainly in the field of language, including several Penguin books, but he is perhaps best known for his two encyclopedias for Cambridge University Press, The Cambridge Encyclopedia of Language and The Cambridge Encyclopedia of the English Language (3rd edn 2018). Recent books include A Date with Language, Let's Talk: How English Conversation Works, and A Life Made of Words: the Poetry and Thought of John Bradburne. Co-authored books include Words on Words (2000, a dictionary of language quotations compiled with his wife and business-partner, Hilary - Wheatley Medal, 2001), Wordsmiths and Warriors: the English-Language Tourist's Guide to Britain (2013, with Hilary), and Shakespeare’s Words (2002), The Shakespeare Miscellany (2005), The Oxford Illustrated Shakespeare Dictionary (2015), and Everyday Shakespeare: Lines for Life, the last four in collaboration with son Ben. A new version of the glossary went live online in 2008, and a 3.0 version launched on 23 April 2018: He was Master of Original Pronunciation at Shakespeare's Globe during 2004-5, working with the companies on OP productions of Romeo and Juliet (written up as Pronouncing Shakespeare, 2005, updated edn 2019) and Troilus and Cressida (2005), and since then has advised on many OP productions around the world.

His books on English phonetics and phonology include Prosodic Systems and Intonation in English and The English Tone of Voice. His clinical books include Introduction to Language Pathology, Profiling Linguistic Disability, Clinical Linguistics, and Linguistic Encounters with Language Handicap. His work for schools includes Skylarks (with Jeff Bevington), the Databank and Datasearch programmes (with John Foster), Nineties Knowledge, Language A to Z, Rediscover Grammar, Discover Grammar, and Making Sense of Grammar. His creative writing includes volumes of devotional poetry (Pilgrimage; Happenings); biographies of the Convent and of the Ucheldre Centre in Holyhead; a play, Living On, on the endangered languages theme; a novella, The Encyclopedia Codes; and he has edited the poetry of the British missionary in Zimbabwe, John Bradburne. Performances include a dramatic reading of the St John Gospel, originally as a CD, now available at

He was founder-editor of the Journal of Child Language (1973-85), Child Language Teaching and Therapy (1985-96), and Linguistics Abstracts (1985-96), and associate editor of the Journal of Linguistics (1970-73). He has edited several book series, such as Penguin Linguistics (1968-75), Chambers' Making Sense of English, Academic Press' Applied Language Studies (1980-84), and Blackwell’s Language Library (1978-2012), and co-edited Blackwell's Applied Language Studies (1986-95) and Studies in Language Disability (1974-2006). In the 1980s, he became editor of general encyclopedias for Cambridge University Press, along with their various abridged editions. In 1996 the database supporting these books came under the ownership of AND International Publishers, who began to develop the database for electronic media. As part of his consultancy work with this company, he devised a knowledge management system (the Global Data Model, or GDM) which allows electronic databases to be searched in a highly sophisticated way (UK and US patents). In 2001, both the database and the GDM became the property of a new company, called Crystal Reference Systems, with two divisions: Crystal Reference had as its primary aim the provision of reference data; Crystal Semantics, the provision of systems for document classification, Internet searching, contextual advertising, e-commerce, online security, and related areas. Products of the new regime included editions of The Penguin Encyclopedia (from 2002), The Penguin Factfinder (from 2003), and The Penguin Concise Encyclopedia (from 2003). Crystal Reference Systems was acquired by Adpepper Media in 2006, and he then switched roles to become director of research and development within the firm (to 2009). Adpepper closed the Crystal Reference division in 2008, and general encyclopedia publishing then ceased. He continued to act as a consultant to Adpepper on Internet applications until 2012.

He has been a consultant, contributor, or presenter on several radio and television programmes and series. These include The Story of English (BBC TV, 8 x 1 hour series 1986, consultant), The Story of English (radio version, 18 x 30-min series, BBC World Service, 1987, writer and presenter), English Now and other series for BBC Radio 4, Radio 5, and BBC Wales during the 1980s and 1990s (as writer and presenter), and The Routes of English (as consultant and contributor). Other television work includes Back to Babel (Infonation and Discovery Channel, 4 x 1-hour series, 2000, as consultant and continuity contributor), Blimey (BBC Knowledge, 3 x 1-hour series, 2001, as continuity contributor), The Routes of Welsh (BBC1, 6 x 30-min series, 2002, as consultant and contributor), The Way that We Say It (BBC Wales, 50-min, 2005, consultant and co-presenter), The Word on the Street (BBC1, 2005, 30 mins, as consultant), Voices of the World (Final Cut, 2005, as consultant and contributor), and several programmes for Open University television, beginning with Grammar Rules (1980, as writer and presenter). He was the consultant for the BBC Voices project in 2005 and was consultant for the British Library ‘Evolving English’ exhibition (November 2010 to April 2011), and author of the accompanying book.

He was patron (1992-2023) of the International Association of Teachers of English as a Foreign Language (IATEFL) and is patron of the Association for Language Learning (ALL), president of the Chartered Institute of Editing and Proofreading, the UK National Literacy Association, and the Johnson Society of London, and an honorary vice-president of the Institute of Linguists and the Royal College of Speech and Language Therapists. He is a past honorary president of the National Association for Professionals concerned with Language-Impaired Children, the International Association of Forensic Phonetics, and the Society of Indexers. He was Sam Wanamaker Fellow at Shakespeare’s Globe in 2003-4, and honorary president of the Johnson Society for 2005-6. He has also been a member of the Board of the British Council and of the English-Speaking Union. He received an OBE for services to the English language in 1995, and was made a Fellow of the British Academy (FBA) in 2000. He now lives in Holyhead, where he was chair of the trustees of the Ucheldre Centre (1990-2022), a multi-purpose arts and exhibition centre, and since 2023 honorary president of the Ucheldre Friends Association. He is married with five children (one deceased). A memoir was published in 2009: Just a Phrase I'm Going Through: My Life in Language.