Well, I found this by far the most difficult Guardian crossword to get started on for years. Like some others who have commented here, I went through all the clues without solving one; I don't remember the last time I did that. However, eventually I made a start, and things gradually got easier. However (again like other solvers) I found an unusually large proportion of clues that I could eventually in but couldn't completely parse. For some of those clues when I eventually did fully parse them I really liked them (14 for example) but my COD is without a doubt 5d. I laughed out so loudly when I got that that I was surprised that my wife didn't ask me what on earth it was about. There are still six clues that I don't fully understand, but I've had enough, and will leave it there.