This is a concise overview of the Welsh sources for 'King Arthur', which at the same time manages to acknowledge the variety of 'Arthurs' that existed both before Geoffrey of Monmouth made him into an Emperor with a vast empire and afterwards.
As an overview and introduction it does what it claims to do in 98 pages.
Having discussed the sources in chapters that move chronologically, and then tracked the 'careers' of a select few characters, the last chapter, 'Was there an Arthur of the Welsh' suggests; 'It is worth considering the idea that Arthur was often an intrinsically comic character, and that Arthurian tales within the range of literary and story telling material available in medieval Wales, occupied a humorous role, perhaps approximately comparable with comic-strip literature to day.'
He immediately qualifies this by giving example of stories that could not be considered comic by anyone and, acknowledging that is untenable to argue that Arthur invariably had an undignified, slow-witted side to his character, asserts that it may be useful to bear in mind the possibility of such an aspect.
If you put aside the issue of dating these texts, the central problem of using these sources, which he has outlined in his discussions of several of the texts, is the impossibility of knowing how these stories were 'used' by their original audiences and the sense that whatever/however that was, it wasn't the way modern scholars approach these texts.
'...certain assumptions have been made too easily about the figure of Arthur in the earliest Welsh sources, partly through an uncritical use of words such as 'heroic' and partly owing to uncertainty, which still exists, over how to approach certain crucial literary sources such as CULHWCH, RHONABWY and the saints' Lives. There is a danger of reading these texts too subtly, combing them for every last clue to ancient traditions, instead of reading them as works of authors who were putting their won interpretation upon the material, and perhaps intended them light heartedly for the most part, though with very serious aims.'