This thesis considers late thirteenth and early fourteenth century insular history writing in the vernaculars in its multilingual, codicological, and historical contexts. It seeks to explicate the changes in insular historiography after the conquest of Wales and amidst the ongoing Scottish wars. The dominant mode of history writing during this period shifted: the texts examined in the thesis are 'derivative texts', complex assemblages of translations from numerous source texts, compiled and combined into unique, original works. Revising current notions of scribal competency, and arguing for a wider consideration of scribal authorship are fundamental aims of the thesis. By demonstrating the diverse and sophisticated textual lexicons of the authors of derivative texts, the thesis exposes vernacular historiographies as learned productions, written for learned audiences, engaged in intertextual dialogue with more 'authoritative' Latin historiography. Medieval translation is explored throughout, in an attempt to broaden an understanding of the term to include textual and ideological transposition, and overwrite 'compilation' as an acceptable description of these sophisticated and politically engaged texts. Chapter 1 examines the Anonymous Short English Metrical Chronicle as a derivative text, situating the work in its historical context of Edward I's appeals to historiography on the Scottish question at the end of the thirteenth century. Chapter 2 is a detailed study of the chronicles of Robert Mannyng and Pierre Langtoft, arguing for the sophistication of the texts, and complexifying previously monolithic ideas of ethnicity and 'Englishness' in the chronicles. Chapter 3 focuses on the Chronicle of Robert of Gloucester, providing a comprehensive introduction to the text, and offering readings of the ideological agenda of its derivative methodology. Chapter 4 investigates London, College of Arms, MS Arundel 58, a mid-fifteenth century manuscript of Robert of Gloucester's Chronicle with unique and substantive prose interpolations, considering the physical processes by which derivative texts were written.