Why would a banker's wife in London drop all her existing plans in order to go to Montreux in June 1930? This happens In a diary I am translating (not hers, but an invited guest suddenly disinvited. ) All I can think of are - someone at (posh) school there, someone in sanatorium, or last minute offer of a holiday for herself.
Btw I was seriously misled by something that turned out to be an alternative history, that 'reported' a Fascist conference held there. There was a real one, but not until a couple of years later. Beware of alternative histories!