In his account of the reign of King Edward I, towards the end of his Anglo- Norman Chronicle, Pierre de Langtoft indulges in jubilation. At last, he exclaims joyfully, all problems with the Scots, who for many years had so unwisely and treacherously resisted Edward's insistence on English overlordship, have been solved. Merlin's prophecy that one day the two nations will be united has finally been fulfilled; Arthur himself never did better:

In the first part of his work, Langtoft had emphasized the importance of Merlin’s prophecy of insular unity by the use of Latin, the language also in which the prophecy to the same intent by the goddess Diana is given. The author's overriding concern, unity in Britain under one king, Edward I, is thus made clear from the beginning of this lengthy verse chronicle, which lists the kings of England in chronological order, and judges them on the efficacy of their relations with the Scots. Of all these kings, it is King Arthur who provides a perennial example.

The statement, quoted above, that unity between England and Scotland has been achieved, is remarkable as at the time of writing, c. 1305–1307/8, the problems with the Scots that had dogged Edward I after the death of King Alexander III of Scotland in 1286 were anything but solved. Langtoft, a politically astute and well-informed chronicler especially on Anglo-Scottish relations, must have been aware of this. King Arthur is associated in the Chronicle with a number of monarchs, but never more prominently and frequently than with Edward I, although ultimately not always favourably.