Back here in Pedants' Corner, mutabilitie, the "-ise/ize" thing is one of my pet peeves* too!
I don't believe spellings had been standardized back in Tudor times (hence Anne Boleyn/Bullen/Boleyne/Bulleyne and no doubt further variations). The Oxford Dictionary gives the "-ize" spelling as correct - except (and since this is the English language of course there has to be an exception) if the word is derived from the French, such as "surprise" where the "s" is correct. It's probably something academics have been arguing about for years and will likely continue to do so!
On the other hand, language is
continuously evolving, and I was wondering if we were seeing this in action in the spelling of "laboring" back in 1915.
(* - not my biggest pet peeve though, which is "could of
, should of
" - that really has me jumping up and down screaming and tearing my hair out!)