Flavours of English

Alex Barnett’s observation that American English is more efficient than its British English cousin got me thinking about the language of my native Canada.  I wonder to what extent Canadians use British spelling versus American ones?  I remember Canada fairly well—I lived there until I was 12—I’m less clear on the nuances of spelling.  I clearly remember using the French spellings of some words—centre, theatre, and metre, for example, I don’t remember having to remember to drop a “u” from words like “flavour” and “colour”, or changing “s” to “z” in words like “customise” and “galvanise” once I moved to the US.  Were American spellings used for those words where I lived?  Or were the British spellings used, and my exposure to American television, which we watched routinely via the rabbit ears, had acclimated me to the American variants?