Hello Deacon, thanks for the kind words. Your wording is better regarding territory, but I think that it still might specifically mention the Firth of Clyde, since Northumbria ruled the area south of it for a while ... how about "between the Humber and the Firths of Clyde and Forth", or similar? But there's no great preference here either way.

Oswiu chose the Roman way at Whitby in 664, and he died in 670; thereafter there was a steady erosion of Iona-based clerics in Northumbrian territory, quite noticeable by Pehthelm's consecration in the 8th century ... have a look at the Skene reference I cite, which suggests that both Picts and Northumbrians were working in concert in the early 8th century towards the Roman way in preference to the Columban way.

It looks like a political process, constant and steady, but not a sudden, forcible ouster ... the end result was indeed a facilitation of Northumbrian hegemony. Northumbria's fortunes were up-and-down in the 7th century regarding its southern neighbors, particularly Mercia, and that is not to suggest that anyone chose Deiran preferences over Bernician ones. I'm aware of the substantial history of Iona-based clerics in Bernicia, but times change (and sometimes political entities do things for expedient reasons).

The translation of Pehthelm's name without stated authority is indeed sourced ... the claim is made flat-out, so have a look at the reference cited; I tried to make sure that anyone who likes to check out references can do so easily ... indeed, you should be able to quickly access every citation that I made in the article. Regards,