And in Three Go, Mary-Lou is still an ordinary little girl cutting the toes off her favourite sandals so they last longer and hanging around with unsuitable bohemian-artists'-child Clem and Tony. Not the appallingly bumptious know-all she turns into.
And I like that Verity is a stubborn, self-willed, independent type in Three Go, not the useless, clingy person she seems to personality-change into overnight in the Swiss books, when she gets reinvented as someone weak that Mary-Lou has to carry as well as Doris Trelawney.
And actually, though it never occurred to me as I was reading the books as a child (probably because I read them out of order, and was skipping gaily about from Armishire to Tyrol to Switzerland at random) -- of course you would have had girls like Verity (and not just English ones, either) who in the years immediately after the war felt deeply uncomfortable or actively traitorous singing German songs or speaking German.
Even if it wasn't an issue for mistresses and girls who'd been at the Tyrolean CS, it would be pretty naive to think that, say, a new CS girl from somewhere like Coventry or somewhere else badly-bomb damaged, or who'd lost family in the war, would necessarily have been thrilled with functioning in German one third of the time just after the war.