I know I've heard or read this - maybe it'll come back where. Anyway, I'd say it's a lot older then the 1964 that Mr J Atkinson reckons it at (I tried Google with the first line too". Start of the last century I would guess, if not earlier. (And I could be completely wrong there.)

But when I followed up Castles in the Air, which was the name Mr Atkinson thought might be the name of it, in that link from Google, I came across this charming song with a midi attached - nothing to do with the one with the quote, but a great example of how if you look for one lost treasure you can always find another you weren't looking for: Castles in the Air, by James Ballantine (1808-1877).