The student of the book in early medieval Wales, and also in those other areas that remained British-speaking, labours under a modest handicap: there are no surviving books known to have been written in Wales or Cornwall before the ninth century. From the British-speaking kingdoms of northern Britain there survive no books at all. The history of the British book must, therefore, be written by circuitous processes of reasoning: by inference from texts written by Britons but only surviving in later and non-British manuscripts, from other modes of lettering, notably inscriptions on stone, and, finally, from comparison with Ireland. The comparison with Ireland is justified because it was part of the one Insular cultural province; not only did it have the same scripts, essentially the same orthography for Latin texts, the same methods of constructing a codex, but current practice usually evolved in the same direction and at much the same time. Moreover, in the early part of our period, there were Irish colonies in Britain, including Wales, and British missionaries in Ireland; even in a later period, there is ample evidence of continued scholarly and ecclesiastical links across the Irish Sea.

There are two fundamental reasons why the distribution of surviving manuscripts cannot be taken as an indication of the usage of books. First, to stick to a position so closely dependent upon one category of evidence would entail a lack of consideration for other categories of evidence, especially texts and inscriptions. Second, it would be to forget that, in general, pre-Norman Welsh manuscripts survived only if they were taken to England in the tenth century and were there preserved in ecclesiastical libraries. Similarly, it is broadly true that early Irish books survived only if they were taken to Francia or to Italy in the eighth or ninth centuries. English books survived somewhat better because they travelled along both routes to preservation – Francia in the eighth and ninth centuries and into the libraries of reformed English monasteries and cathedrals in the tenth century.