Hands up all those who knew O Canada worked as a canon! I was very surprised to discover this fact, and I produced a choral version that can be sung simultaneously in English and French! More recently, I have also arranged it for solo voice and piano.
"How did you do that?" I hear you ask, "That's brilliant!" Well, the English and the French words are both printed in each part (since Canada is officially bilingual), and since the sopranos and tenors
Ok, you can see from the paragraph above that it's not a strict canon. The sopranos take the melody and the tenors indeed sing in canon with them, while the altos and basses provide the harmonies. Those harmonies are striking and rich, and may come as a surprise at first, especially the modulation from F to Ab at the line "God keep our land/Et ta valeur". It sounds like it might be jarring, but in fact it is smooth as silk and really lifts the feeling of the anthem. I hope people will come to enjoy it!
The piano version differs slightly, in that the "canon" must remain in the piano accompaniment, which of course the pianist must try to bring out. The part is not difficult (even I can play it!), and I have removed the modulation to Ab in order to keep the voice line from going above an F (the choir sopranos and tenors go up to Ab). It is a most effective arrangement and it was premièred in Yerevan, Armenia, by myself and my wife, singer/director Andrea Mellis, at a reception honouring 25 years of Canada/Armenia relations.