I liked Toby a lot too, but I did think the Ark of the Covenant obsession was a bit far-fetched even by the standard of school stories.

Are the Dimsie characters Lesley and Ursula? I wondered if they had wandered in from one of her other books, as such a thing was made of the name of their school. (And what is it with marrying friends' brothers? Is it just a reflection of how narrow most girls' lives were, or are they all secretly sublimating their feelings for their friends into feelings for their brothers?)