Well, this rather improved on me quite a bit upon a reread! I still love the humor (for once, virtually without the sarcasm that is present in so many of Heyer's other books), Vicky and her mother are pure sparks of joy, and I even remembered the solution (though definitely not all the technical bits, which in fact I'm bound to have forgotten all over again by later today probably). Now if only Heyer didn't have a penchant for making at least one part of the HEA element of the resolution feel quite so much like insta-love in practically every single one of her books ... (or, well, her mysteries, anyway).