The myth survived
From our UK edition
You may find this book irritating. A complex exposition of 2,000 years of history, it is intended for the general reader, whoever he is (a general reader would surely not attempt it), so its source material is not identified but tidied away into long footnotes, presumably on the principle of pas devant la bonne. Thus the 12th-century historian William of Newburgh is introduced in the main text only as ‘a crusty old scholar’, and the family of Geoffrey of Monmouth as ‘the Monmouths’. All right, so Simon Young thinks he knows his readership. Yet he has this for an epigraph, ‘Ac nyt oed uawr yna y weilgi : y ueis yd aeth ef’, a sentence he attributes, cryptically, to ‘Branwen’.