I've completed the grid, and found - I thought - all of both stories, but two parts of the LH story share a letter, so my grid has only 42 cells highlighted. Is that as it should be, or have I missed something?
Two parts of the DW story also share a letter. I had two blocks of 12 (one for each story) then DW had two five-letters words (which shared a letter).The LH part has a six-letter word and a five-letter word which shared a letter.
Thanks for explaining that - at least I now know where to look. My right-hand story has a 6-letter word (undoubtedly correct) plus an equally plausible 3-letter word on a diagonal. I'll stare at those letters for a while.