The political, ecclesiastical and cultural interactions that I have outlined so far brought speakers of different languages into contact. In this chapter, I investigate the evidence for Gaelic linguistic influence in the Northumbrian kingdom, tracing several different channels and chronological contexts. Bede's famous depiction of King Oswald's collaboration with Bishop Áedán provides some insight into the theme:

Bede's portrayal of this partnership drew on biblical models of Christian kingship and a Gregorian vision of the episcopal life. Oswald's translation of the sermon was in line with St Paul's approach: ‘If I do not know the meaning of the language, I shall be a foreigner to the speaker and the speaker a foreigner to me.’ The portrayal of Oswald and Áedán as Gaelic speakers seems realistic given that both men had spent time in Argyll and Ireland, but how common was this experience in the Northumbrian kingdom? Did the two men belong to a wider Gaelic-speaking community, or were they members of a small, mobile group of noblemen and clerics?

There is a burgeoning scholarship on medieval multilingualism, which tackles the theme from various angles. Scholars have studied texts in search of terms borrowed from other languages, and analysed the circumstances in which vocabulary was borrowed or adapted.5 The influence of texts composed in different linguistic milieus is a topic of enduring interest, as noted already in relation to Cogad Gáedel re Gallaib and the postulated Brjáns saga, a lost Norse text that was later incorporated into Njáls saga.