I happened on this (extinct) language/dialect a couple of days ago on Twitter and I am hooked. It seems to be a mixture of Anglian (Englis) and Cumbrian, with a definite “Geordie” twang.
Strangely, I seem to be able to understand it 
Tagging @dougewart out of interest: It seems to be based in today’s NE England and SE Scotland.
Thanks @JohnYoung, I had a look at this and found that a lot of the words were similar to Norwegian too: - rabbit, house, Easter, etc.But there are many Scandinavian words in the local dialect along the English / Scottish Border.
Yes, that through me slightly. Although no dates were give, I took the Kingdom of Beornis/Bernicia to be based in the 6th c, with the Vikings coming over in the 8tn & 9th c. Perhaps I’m missing something or just taking it too seriously 