refusal. If you can give me an actual cite of the term in print from the 1950’s or 1960’s in British works, I’d dearly love to see it. It doesn’t exist, IMHO. The sites you offer are rather modern and offer no actual cites from 1950-1980. Unless I missed it. There is NO evidence that it predates a 1960’s US usage.
The American Dialect Society Mailing List is still actively discussing this. These guys, both US, British, and other, are pros. I’ll try to post further updates.