This isn't a Viking fish, despite appearances. It's a pair of mittens, knitted traditionally by a present-day Viking with wool from sheep that graze the island of Birka; once centre of Viking trading. We visited this summer, on a house swap to Falun, and our excellent hosts suggested several places to research. Birka was one of our favourites, so I'll attach some more pictures at the end of this update. 

I'm writing now with two pieces of good news: firstly, thanks to your support, The Book of Bera has been well received in hardback and is coming out in paperback next April - so if you have wanted to give a copy to a friend it's a good option. Secondly, I'm about to launch the sequel, OBSIDIAN. So watch out for the mittens!