Mattrom, and so it is. No idea how I missed that. Thanks. And thanks to the setter as I enjoyed the puzzle and also enjoyed finding out about the source.
I have completed the endgame but I have one loose end. I can't parse 3d to give me the letter I need (possibly like Iratus @#4). The wordplay seems precise to give the first three letters but I need one of them to be the 5th letter of the unjumbled word. Can anyone help me tidy this up?
Thanks, JBird54, that's fine, helpful. I knew the preamble mentioned blanks, but didn't know if the number mentioned was significant. I haven't done the puzzle.