Quoted for truth.Proper "British" spelling? You mean French spelling, don't you? Theatre, metre, tyre ... oh wait. Okay, okay, so tyre is British, I guess, if you ignore the city in Lebanon of the same name.
BTW, "British" orthography is just as correct as "American" orthography. Or rather, British Orthography is "correct" for Brits (and Australians, and New Zealanders, et al.) whereas American orthography is correct for Americans. Just as much as "color" would seem incorrect for Brits, "colour" would seem incorrect for Americans (unless said Americans are trying to sound pretentious).
For instance, I can easily make a point that "Autumn," as a latinate word, seems out of place next to "Winter," "Spring" and "Summer," all which are Germanic. Also, I could say that "Fall" contrasts "Spring" in a way that "Autumn" doesn't (flowers "spring" up in the spring; leaves "fall" down in the fall).
So be careful when saying your orthography is the one true orthography, because I could very well make an argument in the opposite direction. However, that's not what I believe. I believe that British and American orthography are equally valid in their respective regions.
My point? Rather than saying that your English is "proper English" say that it's "British English." It's a more neutral, less arrogant term.