This thesis started life as a short, illustrated dissertation on early Christian inscriptions in Wales for a lettering and graphics course at Newport College of Art in 1965. In 1995 I returned to research on the subject for an M. Phil. under the supervision of Miranda Aldhouse Green at the University of Wales, Newport, into which the Art College had been absorbed, and of John Higgitt at the University of Edinburgh. I was very grateful to UWCN to be awarded a bursary to enable me to undertake my M. Phil. Both my supervisors helped me to formulate and improve the ideas that had absorbed me since I was an art student. In the early sixties as a pre-diploma student at Cardiff College of Art I was fortunate to come under the influence of the lettering historian J. C. Tarr and went on to specialise in lettering at Newport under Harry Meadows who had been a pupil of M. C. Oliver -a pupil of Edward Johnston's. I was again fortunate, working as a book designer in Ireland, to be befriended by Rene Hague, the son-in-law of Eric Gill, with whom I learned brush lettering on fabric and cut lettering in wood, using Gill's chisels. Rene Hague was at that time writing his memoir of David Jones and encouraged me to look closely at his inscriptional work. Both David Jones and J. C. Tarr were fascinated by the fate of the Roman alphabet in the Dark Ages. With Thomas Charles-Edwards from 1975 a shared interest has been the early Christian inscriptions of Britain and Ireland. Very aware of the fact that there might be bonds between young apprentices and old masters, this thesis operates chronologically within the Group I and II time spans used by V. E. Nash-Williams. It is convenient that these spans are loosely defined; unless some new find with a specific dating fix appears, closer dating would seem speculative. The scribe of the manuscript known as the Cathach was of some age, with failing sight, but greatly venerated as a scribe. We know that apprentice scribes were youths with sharp sight. The scribe of the Cathach, who is writing in a primitive, prototype `half-uncial', with many features unstabilised that would be stabilised later in canonical half-uncial, would have trained up young scribes in a version of his own hand. There might have been half a century discrepancy in their ages. In any ll craft, this discrepancy in age between master and apprentice clearly blurs the edges of any layering of chronology based on stylistic features; in Britain and Ireland during the Group I period, additionally, there is the problem that for a period of time scripts could have fossilised or deteriorated in the event of a decrease in literacy and the circulation of books. Therefore it seemed prudent to remain within the looser chronology of Nash-Williams.