Publications include William Langland (1993); Pursuing History: Middle English Manuscripts and their Texts (1996); A Descriptive Catalogue of the Western Medieval Manuscripts of St John’s College (2002); ‘Yorkshire writers’, in Proceedings of the British Academy 121 (2003); ‘The Wife of Bath’s Prologue’, in R. Correale and M. Hamel (eds), Sources and Analogues of the Canterbury Tales II (2005); London Literature, 1300-1380 (2005); ‘John Dygon, fifth recluse of Sheen: his career, books and acquaintance’, in J. Thompson (ed.), Imagining the Book (2006); The Knightly Tale of Golagros and Gawane: A Critical Edition (2008); ‘Some North Yorkshire scribes and their context’, in G.D. Caie & D. Renevey (eds), Medieval Texts in Context (2008); ‘Lambeth Palace Library, MS 260 and the problem of English vernacularity’, in Studies in Medieval and Renaissance History 3rd ser. 5 (2008); Speculum Vitae: A Reading Edition (2 vols, 2009); The English Manuscripts of Richard Rolle: A Descriptive Catalogue (2010) .

Research interests include Piers Plowman and alliterative poetry, language contact and concepts of regional community in medieval England, and English manuscript books.