The Tudor period saw a revolution in antiquarian histories of Britain. Their networks of transmission largely circle around major collectors such as Matthew Parker and William Cecil. One prominent figure in Cecil’s orbit was Laurence Nowell, the antiquarian whose name is famously associated with the Beowulf manuscript (the “Nowell Codex”). Nowell made copies of the Itinerarium Kambriae and Descriptio Kambriae, both texts by Giraldus Cambrensis, from differing sources, resulting in the defective manuscript London, British Library Additional MS 43706. His colleague William Lambarde used the Add. MS 43706 as the basis for his copy of Descriptio Kambriae. However, before Lambarde finished his transcription, he made annotations in Nowell’s copy. This paper will examine the marginal annotations in Add. MS 43706, which include several annotations in Nowell’s hand too. Nowell and Lambarde must have exchanged the manuscript back and forth, as demonstrated by their crossing out and correcting of each other’s annotations. This correspondence on the physical pages of the manuscript speaks to their differing attitudes towards prominent aspects of Giraldus’s text, including how to read and interpret marvels, natural history, and the twelfth-century discord between Wales and Anglo-Norman England. Nowell’s more conservative attitude led him to derisively identify many of the anecdotes as “superstitio”, “ridiculum”, and “fabula”, whereas Lambarde resists such disparaging comments by crossing them out and then justifying them with notes such as “mais miraculu[m]”. This article ultimately argues that reading conflict in the margins highlights the value of studying marginalia in order to better understand the transmission practices of the antiquarians, including how they read medieval texts and how they interpret, translate, excerpt, and summarize them.