For my part, I'd have guessed that it was chiefly AE, simply because it's not part of my active vocabulary, either. That said, I wasn't baffled or surprised by this thread, so perhaps it was already lingering somewhere on the periphery of my consciousness.

The Google Books NGram viewer suggests that it is in fact slightly more common in UK English, where its occurrence has gone up sharply since 1980. Use in the US seems to have risen in recent decades, but more gradually. See: Google Ngram Viewer . Whether that reflects conversational use is hard to say.

The first writer linked by amw is from the US and thinks it was an old-fashioned colloquialism wherever he grew up (possibly Chicago, if the byline is a clue):

"It’s an expression I heard a lot growing up in a working-class family decades ago and still hear among the old-timers of my generation".

Incidentally, if I run it through a variety of search engines, I get a preponderance of hits from US speakers even if I tell the site to focus on the UK - but whether that proves anything, I don't know.