Double Star by Robert A. Heinlein
Glad you mentioned Ruritania, since Double Star makes me think as well of The Prisoner of Zenda. And the Prisoner of Zenda always reminds me of Jack Lemmon in The Great Race :)
Glad you mentioned Ruritania, since Double Star makes me think as well of The Prisoner of Zenda. And the Prisoner of Zenda always reminds me of Jack Lemmon in The Great Race :)