In fact, I've just seen another possible solution to #57. It might even be the original solution I had in mind when I first posted it (I wrote it a couple of years ago and never kept a record of the answers, so I have to try to work out the answers to my own puzzles sometimes!!)
I don't really like #57, because I try to make the puzzles such that there is a reason why the odd one out is odd, ie. a reason why I chose that clue rather than some other, rather than just being three things that fit together and one that doesn't. So the original #57 really doesn't meet my normal quality control standards
Sorry.
I've redrafted it, and come up with two new puzzles instead, to reflect the two possible answers I had in mind.
#57a.
(a) Digory and Polly's (first) visit to Narnia
(b) The first time all four Pevensies visited Narnia
(c) The second time all four Pevensies visited Narnia
(d) Eustace and Jill's final visit to Narnia
#57b.
(a) Digory and Polly’s visit to Charn
(b) Digory and Polly’s (first) visit to Narnia
(c) Lucy's first visit to Narnia
(d) Eustace and Jill's final visit to Narnia
I'm still not 100% satisfied with #57b as a question, but it's definitely better than the original #57.
I do hope someone will have another crack at #61. I think, of all the puzzles I have posted in this thread, that one is possibly my favourite so far. If you know the Chronicles well, it is quite solvable, but if there's a bit you don't remember it might require a collaborative effort to solve it - so even if you don't have the solution, do post your partial thinking on it (or any other problems) and see if it sparks someone else's thoughts. And do check out the tips I gave on how I set the problems (and therefore on how to solve them) in post #465. The purpose of these puzzles, as well as to be fun, is to make you think, and to make you notice details you might not have seen before, thereby helping develop a knowledge of the Chronicles, and even perhaps sparking spin-off discussions on them.
Peeps