David Willis is a Reader in the Department of Theoretical and Applied Linguistics. He specialises in historical linguistics and in theoretical and dialect syntax, working primarily on material from Celtic and Slavonic languages (especially Breton, Bulgarian, Russian and Welsh). He has published books on word-order change in Welsh (Syntactic change in Welsh: A study of the loss of verb-second, 1998, OUP), on Welsh syntax (The syntax of Welsh, 2007, CUP; co-written with Bob Borsley (Essex) and Maggie Tallerman (Newcastle)) and on the diachronic evolution of the syntax and semantics of negation (The history of negation in the languages of Europe, Part I: Case studies, 2013, OUP; co-edited with Anne Breitbarth (Ghent) and Chris Lucas (SOAS)). He is interested in the mechanisms of syntactic change, particularly theoretical approaches to degrammaticalisation and exaptation, in syntactic reconstruction, and in the use of electronic corpora in historical linguistics (for instance, as part of the Historical Corpus of the Welsh language 1500-1850). He was principal investigator of the AHRC-funded project on the history of negation across European languages(especially Jespersen's cycle), and has recently begun looking at ongoing variation and change in contemporary Welsh, as part of the Syntactic Atlas of Welsh Dialects.