Thanks so much, everyone - it's amazing to see some familiar names from a long time ago!
It really did come as a complete surprise to me as well - I was struggling getting the narration part to sound right myself and then remembered about the series introductions in Knightmare and how his voice was absolutely perfect for over-the-top pretentious metal concept albums... so I looked up his agent, sent an email to her and she (being an incredibly nice woman!) just... sorted it all out. (I definitely had to carefully word the detail that the story was "based on the works of a Japanese author called Hato Moa" and desperately hoping she didn't Google it.) Even so many years on, I'm still not quite used to being an adult and being able to ask people to do things.
I'm back on a Knightmare kick now thanks to this