I’m prepared to partially rescind my earlier criticism of Ruey. It does pick up the pace after half term (which is itself a whirlwind of private flights and chauffeured limousines, or what the papers would call ‘a secretive network of billionaire businessmen and elite international families’). For whoever it was who asked - it is indeed the one where her dad and another chap, sadly unnamed, take off for the Moon. And I cannot recall whether, in any later book, they are ever heard of again.
Jemima ... Nah, mate. Maybe Madge was too infatuated with Sir JT to admit the obvious. The man probably fathered half the offspring born to doctor-marrying ex-Chalet School teachers resident within 100 miles of the San. (I am reminded of a recent case in the news concerning, IIRC, an ivf Doctor ...)
Although - to be frank, it seems highly likely that the local peasant population provided erm, social entertainment for the school population.
Speaking of entertainment - this is also the book in which Misses Wilmot and Ferrars use their free weekend to travel down to Basle together ‘to attend some university lectures’. 
I’m certain EBD knew exactly what she was saying. And it seems to me those two had a rather enviable life set up. Just think of them gradually promoted into solid wealth and eventually retiring together to an apartment in some cool European city ...