Dr Ben Guy

Assistant Professor in Celtic

Contact Information

Department of ASNC
Faculty of English, 9 West Road, Cambridge CB3 9DP


Office: S-R35 (+44-1223-767312), email: bdg25@cam.ac.uk

Departmental and College Responsibilities

  • Teaching in medieval Welsh language and literature (ASNC Part I, Paper 7; Part II, Paper 7)
  • Teaching in Celtic Philology (ASNC Part II, Paper 12)
  • Supervision of graduate students in Celtic languages, literatures and history
  • Deputy chair of examiners for ASNC
  • Library officer for ASNC
  • Cambridge Festival coordinator for ASNC

I am also a fellow of Fitzwilliam college, and Director of Studies for ASNC in both Fitzwilliam and Selwyn.

Academic Interests

Medieval Welsh language and literature; medieval historical writing, especially genealogies, chronicles and origin legends; early Insular history, especially relating to Anglo-Welsh interaction; Welsh manuscripts; Celtic philology, especially the development of Old and Middle Welsh

Other academic roles:

Selected Publications


‘A New Era for Welsh Manuscript Studies’, The Library 25 (2024), 88–95.

‘The Distribution of 3. pl. pres. ind. –(h)yn(t) and the Dating of Welsh Prophetic Poetry’, Journal of Celtic Linguistics 25 (2024), 47–80.


‘“O Achaws Nyth yr Ehedydd”? Enwau Lleoedd a Chwedl Myrddin’, Llên Cymru 46 (2023), 1–10.

with Rory Naismith, ‘Lancaut: An Early Eleventh-Century Mint-Place on the River Wye’, British Numismatic Journal 93 (2023), 95–105.

‘Manaw of the Britons: The Pre-Viking Kings of the Isle of Man’, Isle of Man Studies: Proceedings of the Isle of Man Natural History and Antiquarian Society 18 (2023), 145–61 [OPEN ACCESS].

‘Explaining the Origins of Brittany in the Twelfth Century: St Cadog's Solution’, in Multi-disciplinary Approaches to Medieval Brittany, 450–1200: Connections and Disconnections, ed. C. Brett, F. Edmonds and P. Russell (Turnhout: Brepols, 2023), pp. 239–62.


Offa's Dyke Journal 4, Special Issue: Borders in Early Medieval Britain, ed. B. Guy, H. Williams and L. Delaney (2022), pp. i + 176 [OPEN ACCESS].

‘The Changing Approaches of English Kings to Wales in the Tenth and Eleventh Centuries’, in Offa's Dyke Journal 4, Special Issue: Borders in Early Medieval Britain, ed. B. Guy, H. Williams and L. Delaney (2022), pp. 86–106 [OPEN ACCESS].

‘The Vespasian Life of St Teilo and the Evolution of the Vitae Sanctorum Wallensium’, in Seintiau Cymru, Sancti Cambrenses: Studies on the Saints of Wales / Studies in the Saints of Wales, ed. D. N. Parsons and P. Russell (Aberystwyth: University of Wales Centre for Advanced Welsh and Celtic Studies, 2022), pp. 1–30 [OPEN ACCESS].

‘Origin Legends and Genealogy’, in Origin Legends in Early Medieval Western Europe, ed. L. Brady and P. Wadden (Leiden: Brill, 2022), pp. 363–84.


‘Misunderstanding Old Welsh Orthography and Insular Script in the Jesus College 20 Genealogies’, Celtica 33 (2021), 59–96.


Medieval Welsh Genealogy: An Introduction and Textual Study, Studies in Celtic History (Woodbridge: Boydell, 2020).

The Chronicles of Medieval Wales and the March: New Contexts, Studies, and Texts, ed. B. Guy, G. Henley, O. W. Jones, and R. Thomas, Medieval Texts and Cultures of Northern Europe (Turnhout: Brepols, 2020), pp. xvi + 455.

‘Historical Scholars and Dishonest Charlatans: Studying the Chronicles of Medieval Wales’, in The Chronicles of Medieval Wales and the March, ed. Guy et al. (see above), pp. 69–106.

Brut Ieuan Brechfa: A Welsh Poet Writes the Early Middle Ages’, in The Chronicles of Medieval Wales and the March, ed. Guy et al. (see above), pp. 375–419.

‘Geoffrey of Monmouth’s Welsh Sources’, in A Companion to Geoffrey of Monmouth, ed. G. Henley and J. B. Smith, Brill Companions to European History (Leiden: Brill, 2020), pp. 31–66 [OPEN ACCESS].

‘The Reception of Geoffrey of Monmouth in Wales’, in A Companion to Geoffrey of Monmouth, ed. G. Henley and J. B. Smith, Brill Companions to European History (Leiden: Brill, forthcoming 2020), pp. 494–7 [OPEN ACCESS].


'Rheinwg: The Lost Kingdom of South Wales', Peritia 30 (2019), 97–121.

‘Writing Genealogy in Wales, c.1475–c.1640: Sources and Practitioners’, in Genealogical Knowledge in the Making: Tools, Practices, and Evidence in Early Modern Europe, ed. J. Eickmeyer, M. Friedrich and V. Bauer, Cultures and Practices of Knowledge in History 1 (Berlin: de Gruyter Oldenbourg, 2019), pp. 99–125.


‘Constantine, Helena, Maximus: On the Appropriation of Roman History in Medieval Wales, 800–1250’, Journal of Medieval History 44 (2018), 1–25.

‘The Earliest Welsh Genealogies: Textual Layering and the Phenomenon of “Pedigree Growth”’, Early Medieval Europe 26.4 (2018), 462–85 [OPEN ACCESS].

‘The Life of St Dyfrig and the Lost Charters of Moccas (Mochros), Herefordshire’, Cambrian Medieval Celtic Studies 75 (2018), 1–37.

‘Gerald and Welsh Genealogical Learning’, in Gerald of Wales: New Perspectives on a Medieval Writer and Critic, ed. G. Henley and A. J. McMullen (Cardiff: University of Wales Press, 2018), pp. 47–61 [available on Google Books].


Edition of the Life of St Clydog (published online 12/09/19)

Edition of the Life of St Dyfrig (published online 02/03/20)

Edition of the Life of St Euddogwy (published online 25/04/22)

Edition of the Life of St Teilo, Book of Llandaf version (published online 22/04/22)

Edition of the Life of St Teilo, Vespasian version (published online 22/04/22)

Edition of the Life of St Samson, Book of Llandaf version (published online 19/09/23)


‘A Lost Medieval Manuscript from North Wales: Hengwrt 33, the Hanesyn Hên’, Studia Celtica 50 (2016), 69–105 [OPEN ACCESS].

‘The Textual History of the Harleian Genealogies’, Welsh History Review 28 (2016), 1–25.


‘Egerton Phillimore (1856–1937) and the Study of Welsh Historical Texts’, Transactions of the Honourable Society of Cymmrodorion, new series, 21 (2015), 36–50.

‘The Origins of the Compilation of Welsh Historical Texts in Harley 3859’, Studia Celtica 49 (2015), 21–56.


‘A Second Witness to the Welsh Material in Harley 3859’, Quaestio Insularis: Selected Proceedings of the Cambridge Colloquium in Anglo-Saxon, Norse and Celtic 15 (2014), 72–91.

‘The Breton Migration: A New Synthesis’, Zeitschrift für celtische Philologie 61 (2014), 101–56.

‘A Welsh Manuscript in America: Library Company of Philadelphia, 8680.O’, National Library of Wales Journal 36 (2014), 1–26 [OPEN ACCESS].


‘Did the Harleian Genealogies Draw on Archival Sources?’, Proceedings of the Harvard Celtic Colloquium 32 (2012), 119–33.


Review of C. Brett, with F. Edmonds and P. Russell, Brittany and the Atlantic Archipelago, 450–1200: Contact, Myth and History (2022), in Studia Celtica 57 (2023), 167–9. 

Review of H. Pryce, Writing Welsh History: From the Early Middle Ages to the Twenty-First Century (2022), in The Medieval Review (2023) [OPEN ACCESS].

Review of D. W. Burchmore, The History of the Kings of Britain: The First Variant Version (2019), in Journal of Medieval Latin 32 (2022), 300–6.

Review of K. McCann, Anglo-Saxon Kingship and Political Power: Rex gratia Dei (2018), in Speculum 97 (2022), 224–5.

Review of W. MacQuarrie and J. F. Nagy, eds, The Medieval Cultures of the Irish Sea and the North Sea: Manannán and His Neighbours (2019), in Journal of English and Germanic Philology 120.2 (2021), 245–7.

Review of M. F. Stevens, The Economy of Medieval Wales, 1067–1536 (2019), in The Medieval Review (2021) [OPEN ACCESS].

Review of R. Flechner, Saint Patrick Retold: The Legend and History of Ireland’s Patron Saint (2019), in Kelten 83 (2020) [OPEN ACCESS].

Review of P. Sims-Williams, The Book of Llandaf as a Historical Source (2019), in Morgannwg (2020), 225–9.

Review of Michael Powell Siddons, Welsh Genealogies A.D. 1500–1600 (WG 3) (2017), in Welsh History Review 29 (2019), 480–2.

Review of Lindy Brady, Writing the Welsh Borderlands in Anglo-Saxon England (2017), in English Historical Review 134 (2019), 947–9.

Review of Lynette Olson, ed., St Samson of Dol and the Earliest History of Brittany, Cornwall and Wales (2017), in English Historical Review 134 (2019), 1767.

Review of David Stephenson, Medieval Powys: Kingdom, Principality and Lordships, 1132–1293 (2016), in Speculum 93.3 (2018), 915–17.