Anthony Hope's novels, including The Prisoner of Zenda, resulted in "Ruritania" becoming a generic term for any small, imaginary, Victorian or Edwardian Era, European kingdom used as the setting for romance, intrigue and the plots of adventure novels. His novels spawned a new genre and nowhere was it more successful than in juvenile fiction.
The main plot of Dorothea Moore's novel revolves around HRH Princess Alix who swaps places with plain Miss Molly Smith in order to experience, at first hand, the joys of boarding school. There are many false starts and misunderstandings but all comes good in the end and HRH returns to Anconia, and her brother, the King, a wiser girl. Great stuff!
Elisaveta in Brent Dyer's Princess embodies all of the characteristics of the Ruritanian heroine - desire to experience school and behave "normally", as well as propensity to get into many scrapes throughout the book. She's plucky and loyal and, later in the Chalet School series when Belsornia has been overrun by Bolsheviks and subsumed into the Soviet Union, she is able to live simply as Mrs Helston.
So, I'm on the hunt for more novels in this genre. I've just acquired Dorothea Moore's A Young Pretender which I think is written in the same style.
I believe that Alys Chatwyn's The Head Girl of St Bee's has a Ruritanian theme so I need to check it out soon. I've not read the book before and I always assumed it was set on the West Cumbria coast in the town of St Bees but maybe not.....