User blog comment:Sannse/These Are a Few of My Favorite Wikias/@comment-24898716-20141105155212/@comment-5558012-20141105171055

British English adds a "u" to many words (ie. colour, favourite, flavour, harbour, honour, humour, labour, neighbour & rumour). American English ignores them. While there might not be a "rule," styling stresses that a work be consistent (some based off location of subject). If 100 pages use American English and five use British English you have a consistency problem that should to be fixed (as some editors will see this as spelling errors) just as if all but a few articles of the same type have the same headers. While Wikiapedia states "While Wikipedia does not favor any national variety of English, within a given article the conventions of one particular variety should be followed consistently.," other wikis may or may not go further.