Oisín Plumb sets out his two-part mission very clearly in the opening chapter of Picts and Britons in the Early Medieval Irish Church: Travels West Over the Storm-Swelled Sea. First, he examines evidence for churchmen and women who moved from northern Britain and Pictish territory to Ireland. This he does in a series of three case studies. Second, he investigates the narrative that later writers and cult-keepers shaped around these mobile Picts and Britons, further showing how that migration narrative shifted over time in response to political environments. Plumb focuses on the period between the missionary Patricius's work in Ireland, sometime before 500, and the emergence of the kingdom of Alba (a blend of Gaels, Picts, and Scandinavians that eventually became Scotland) around 900.
Historians and archaeologists have long studied the dense traffic between the two big islands on mainland Europe's northwestern edge. People and their stuff were moving across the North Channel and Irish Sea in the Neolithic. By the fifth century, the Irish had colonized bits of Wales and established the kingdom of Dál Riata that spanned from (what is now) Argyll and Skye to County Antrim in Ireland. Saint Columcille famously went eastward too, taking Christianity to the Hebrides in the 560s, where he established his famous monastery of Iona on land donated by a kinsman (or possibly a Pictish king.)
However, Plumb claims, scholars have not adequately studied the travels of churchmen and women in the other direction. His frequent discussions of other historians’ opinions might suggest otherwise. However, Plumb is the first to look for sustained patterns of ecclesiastical migration to Ireland.
The textual evidence is problematic and scant. Plumb devotes his second chapter to source description, explaining major genres and the ways that texts were composed, transmitted, and revised. This is information is useful for nonspecialists, although most of the books seems directed to scholars in the field. Plumb does his best to explain some major problems with the evidence that are taken for granted by specialists. To begin with, Irish texts do not always identify individual travelers of the fifth and sixth centuries. This may be because many Irish saints’ lives were produced long after their subjects lived; their characters represent political and religious developments of the anonymous writer's (or rewriter's) time rather than the saint's period. Also, authors of martyrologies often combined or even invented traveling ecclesiastics. Monastic annalists got dates and names wrong. To make it harder, many migrants and missionaries had similar names and, what's more, the Irish gave their saints multiple nicknames. As for British and Pictish sources: even scantier or written much later. The difficulty of establishing the identity of individuals and their associated churches is a theme of the book.
Hence Plumb resorts to the history of two famous saints, Patrick and Columcille, as the basis of case studies involving other migrants. He finds that stories of Patrick's British kin and Columcille's web of Pictish allies reveal not missionary travels but, instead, declarations of early medieval church networks that gained prestige by their founder's association with more important holy men. Many Irish cult-keepers assigned British parentage to their founders simply because Patrick's generation of preachers came from Britain. Linking migrants to born-Irish saints in genealogical tracts was like making a treaty between two kingdoms and their churches. Plumb argues that Irish saints with reputed British ancestry may, however, be shadows of historical migrants.
Similarly, Plumb concludes in his second case study that the Uennianus who corresponded with Gildas may not be the same Uinniau who composed a well-known penitential used by Saint Columbanus, nor any one of the several Finnians commemorated in Irish martyrologies, let alone the Findbarr whose name may be strewn across Scottish churches. The Fínáns of Ireland and the Uinniau of Brittany and Wales just confuse things. Were any of them actually the Uinniau described as “a great gift” from Pictonia to Ireland (95)? A Venn diagram of Finnians does not yield a single historical individual. It does, however, show that various Finnians shared enough characteristics to suggest an original Uinniau who crossed the waters. As Plumb sums up, “A survey of the evidence . . . leaves much room for speculation as to the details of the life of any historical person, as well as the way in which their cults might have spread, diverged, and merged” (95).
Plumb's third case study focuses on a poem from the twelfth-century Book of Leinster attributed to Columcille. The poem tells of “the seven beautiful sons of Óengus” who arrived in Ireland to found seven churches. As in previous chapters, Plumb delves into the martyrologies, onomastics, genealogies, hagiographies, and later fair days possibly dedicated to the seven brothers. He concludes that the brothers share characteristics, but no historical individual emerges from the Venn diagram. They probably were not even brothers. However, the churches that several of them supposedly founded in the Irish midlands reflected later territorial claims of the powerful Uí Néill dynasty. Plumb interprets the seven brothers more as markers of migrant routes across the Irish Sea.
Although Plumb cannot pin reliably historical Britons and Picts to a map of Ireland, he interprets the repetition of tropes and the overlap of tenuous references as evidence for consistent movement between the islands. (Information about sea routes and the migration of religious objects and texts might have strengthened his argument.) He detects three “channels of migration” (21) between, first, the far northern Picts and Ireland, via Columcille's network of churches headquartered in Dál Riata; second, between the Pictish heartland and Ireland; and third, between northern Britain and Ireland. Is Plumb's analysis accurate? It is based on texts that were never meant to convey what really (in our terms) happened to actual individuals. Early medieval authors constantly revised the past, just as modern scholars update their conclusions. Shadowy Britons and Picts were not always meant to be seen in daylight.
Plumb's thesis is as plausible as any other interpretation of early medieval depictions of late antique travelers between Britain and Ireland. His main point is persuasive: the travels of British and Pictish ecclesiastics to Ireland, however imperfectly recorded, seemed important to church leaders of the early Middle Ages. Even if Plumb's analysis is riddled with what-ifs and too-eager assumptions, Picts and Britons in the Early Medieval Irish Church remains—to paraphrase Plumb—the embarkation point for future journeys into the twisted history of early Britain and Ireland.
