since no one knows, ill say that ijem you won this one, it's your turn.
the correct answer was: Monaco, with tied Isabelle Aubret's "Le Bonheur" and the winning song and Tereza's "Bien plus fort".. the princess Grace herself, head of the jury for the whole esc period, said that both songs were of equal quality and it was best to give her chance to an unknown singer, so Tereza went instead of esc 62 winner and esc 68 3rd Isabelle Aubret.. Monaco ended last of 1966 with 0pt and France ended 14th with 1pt.. would these two countries, both used of much better results (France had always been in the top 5 before that), have done better with the other song than the one they chose? we'll never know..
ijem, your turn!