just got to this today - very clever, as usual, Hamish - and, as others have said, I thought I would be finished in an hour, only for the last third to take two hours more ... there's something really perverse about filling the answer in with one letter deliberately wrong and no definition to the word you're writing - don't think I would ever get used to that ... I'm certain of the answers to 4 and 7 but, despite the hints given here, still can't really parse them. Thanks again, Hamish - a fun solve.