This one's very much a wartime book: I can't imagine EBD including a spy story like this in the series in any other context. I'm not quite sure why she chose to combine it with her rather bizarre take on people from the Scottish Highlands (which IIRC is similar to that in one of EJO's books), whom she depicts as travelling on trains in full (male?) Highland kit, though!
I think that Robin comes across very well in this - although it's a shame that she seems to have to miss out on time at school due to being "needed at home". So does Elisaveta, who deals very well with a dangerous escape (again something that would only feature in a war book) across Europe, although Belsornia's move from being on the northern Adriatic coast at one point to bordering Turkey in this is rather "interesting". & so does Elizabeth. Joey comes across less well: I get the impression that her reason for taking in Flora and Fiona (BTW, are we meant to know who Jean Mackenzie was
?) was largely to avoid having evacuees from inner cities billeted on her, or having to do any other sort of war work. & don't get me started on why Madge doesn't get involved in war work: it would be totally in character for her to organise knitting circles or something, but she doesn't.I'd love to know what happened to Rosalie after she ended up still, grey and to all appearance dead! Why on earth did neither EBD nor the editors pick up on that?! & the idea that Karl Linders just happened to be flying over the CS and to drop a message on it is very odd indeed!
The second sight storyline's always controversial. I try to keep an open mind about things like that myself, but I find it hard to believe that Hilda, a woman who seems to hold very conventional religious beliefs, would be convinced by it. Also, I appreciate that she meant to try to give Joey hope, but she could easily have been giving her false hope and I can't believe she'd do that. It's completely understandable that Joey wants to clutch at any straw going and to believe that Jack isn't really dead and that there's been a mistake, but I find Hilda's actions to be out of character.
I wish we'd seen more about Jack's return. I read the pb long before I managed to get hold of a copy of the hb and assumed that a big section about Jack's return had been cut, but it hadn't ... he just turns up at the Christmas play and that's the first we hear of his being alive. My great uncle was also reported missing presumed drowned by the Navy during the Second World War and later turned up alive: I'm not sure how common things like that were, but they certainly did happen in real life.
I was waffling about this in another thread recently, but we see a rare emotional side to Jem in this: he's hit very hard by the news of Jack's death.
It's a strange combination of "danger" themes that could only really appear in a wartime book and the second sight storyline which doesn't really fit with the general ethos of the CS books either.
it's always very touching, and when she sees the triplets and says she has to be mother and father to them both, it always chokes me. The second sight issue is a little far-fetched, but yet, as the twins have lived on their little island all their lives, who knows what they might have inherited so-to-speak? I am suprised that they let Fiona try it though, even if to give Joey some kind of comfort, I know they protest a little, the authorities,but give in eventually. 
) a few years ago. The things she went through were well thought about, and I think EBD did put a great deal into it (Did she not dedicate a whole chapter to veta?). I find it quite humbling that a princess would do extremely hard work to keep her family clean and under a roof, etc - it just goes to show that the Chalet School rubbed off well on her, and her early training to think of people before others as a princess and a guide goes a long way.
) the idea of Second Sight in such a 
I would be interested to know whether anybody else has had a change of heart over this book, given the importance of the scene.
It would probably have made the gap between Tirol days and her postwar situation less jarring when I first encountered the latter (I've only ever read the paperback version of any CS book).
, but I do find it odd that there's so little reference to public exams. I wonder why EBD chose to mention them here, unless it's just because it's the first book after they got settled in Britain, but nowhere else.
.
- again, though, I think that was pretty much standard practice for the time - amazing though it seems now.