I was lying awake in bed at 2am, my brain a soup of numbers, when suddenly it all clicked into place. I’d missed a glaringly obvious logical inference which immediately unlocked the whole puzzle. I grabbed a pen and paper, scribbled down a few calculations and slept easy for the first time in three nights 
I’ve now solved the sudoku and it was immensely satisfying! Thank you to those who pointed out the importance of rules 6 & 11.
5 Likes
Sadly ran out of time for this one
1 Like