And in this case, ignoring GrammarBook’s other good reasons for not doing it, the OP would be wrong, as they have clearly over-generalized the incorrect “rule” that “ize” words are “Americanisms” and thus necessarily wrong in “proper” (. British or perhaps Commonwealth) English. I consider Oxford the authority on British English and their online entry for https:///definition/organisation redirects to https:///definition/organization which says “organisation” is also acceptable, but Oxford’s position has always (?) been that there are very many correct “ize” words in British English. Yes, “analyze” is a US English usage and wrong in British English, and there are a few examples where “ise” is preferred to “ize”, but most are not.