Sounds reasonable enough. I looked into my own question as well after I posted it and found this in the askoxford.com FAQ:
"British spelling has always recognized the existence of variant spellings using the suffix -ize/-ise. When American spelling was standardized during the 19th century (mainly through the efforts of the great American lexicographer Noah Webster), the consistent use of -ize was one of the conventions that became established. However, since then, the -ise spellings have become more popular in Britain (and in other English-speaking countries such as Australia), perhaps partly as a reaction against the American custom."
