The post was intended to be a straightforward look at the fact that although American and British speakers differ as to the spelling of the nouns honor/honour, humor/humour, and glamor/glamour, they agree on the spelling of the adjectives honorary, humorous, and glamorous.
I felt secure in declaring that the spellings honourary, humourous, and glamourous are wrong because the Oxford English Dictionaries site lists all three with their “commonly misspelled words.” When I looked the words up in the Oxford English Dictionary, I found that glamourous receives an “also spelled” notation, but that honorary and humorous are the only options. Another source, the WordWebOnline dictionary, flags glamourous as “nonstandard British usage.”
When I went Web-diving for usage examples, I discovered that not all speakers of British English are on the same page as the Oxford dictionaries when it comes to spelling these adjectives:
Wagamese receives honourary degree from Lakehead University –Wawatay News Online (Ontario)
Ryan Giggs ‘tremendously proud’ to receive honourary degree –WalesOnline
Bruce Cockburn to receive LU honourary degree –Sudbury Northern Live.ca
A humourous take on a serious issue –Deccan Herald (India)
A humourous look at our Customer Service (Irish travel site)
A humourous look at weekends at the cottage –muskokaregion.com (Ontario)
I don’t want to spark an international incident, but because my principal authorities for British English usage are the OED and its offshoot the Oxford Dictionaries site, my advice to writers is that honourary, humourous, and glamourous are nonstandard spellings of honorary, humorous, and glamorous.