Inside the front cover of Cambridge, Fitzwilliam Museum MS 346, a copy of Geoffrey of Monmouth's Historia regum Britannie, an eighteenth- century owner notes that he has seen the translation of the work by Aaron Thompson, ‘with a large preface wherein he endeavours to prove the author to be a more faithfull Historian, than he is generally esteemd to be’. The reference is to the first English translation of the Historia, which appeared in 1718 with, as the note says, an extensive preface championing Geoffrey's veracity, in particular with reference to the Brutus foundation story. This was, as I have written elsewhere, quite an extraordinary claim to make by this point in Geoffrey's reception history. Thompson was fighting a battle that had been largely settled, and not in Geoffrey's favour, some centuries earlier. There is nothing in the Fitzwilliam annotator's comment to indicate whether he endorsed Thompson's view or not, though the manuscript itself has added chapter divisions based on the divisions in Thompson's translation, suggesting at least some communication between the two books. What is clear is that a reader of the Historia who had also read Thompson would have a very particular sense of what Geoffrey's text is about. Thompson's preface takes Geoffrey's claim to be translating an ancient British book at face value and sees that book as important because of what it has to say about Britain's origins. Thompson goes to great lengths to take issue with early modern antiquarians who queried the Historia's foundation story, remarking, for example, that William Camden was wrong to argue in his Britannia (1586) that Geoffrey was the first to tell the story of Brutus, saying instead, ‘That there had been frequent Mention made of Brutus the Founder of the British Race, by Authors extant long before Jeffrey's Time; and that there had been a constant Tradition either oral or written concerning him, especially among the Britains, even from the first Beginning of the British Nation’. Thompson does concede that ‘it is very well known that … fabulous and legendary Stories, were very well receiv’d in those credulous Times, and that the gravest Writers are not exempt from them’, specifically mentioning ‘several of the most Romantick and incredible Exploits of King Arthur’, and suggesting that the currency of such tales among the Welsh might explain their appearance in Geoffrey's text.