It's possible the solo album will arrived before Opeth's 12th title - although work has begun on that too. Akerfeldt tells FaceCulture: "I'm thinking of a project that I want to do with a couple of friends. I can probably with confidence say that it will happen.

"I've been thinking about it a lot. I can't get it out of my head, so it means something." He adds: "It will be in Swedish. I asked Dan if he wants to play drums. Another friend is a classically-trained piano player, but he plays bass and has a really cool vintage studio, so I'm thinking of doing something like that.