Apparently it's an animated cel from a commercial for Heinz 'Happy Soup' in the early 60s. These were cartoon commercials for kids' soup, starring Disney characters like Donald Duck, Goofy, etc. Some of the can labels were designed by Floyd Gottfredson, believe it or not. His original designs can be found online, though I'm not sure if this particular one was done by Gottfredson too.
What struck me is that the particular commercial this cel comes from featured uncle Scrooge--and therefore may very well have been Scrooge's first animated appearance ever. Unfortunately I haven't found the commercial online--it may have been lost, although some of the other ones from the series are still available:
Animation was done by FilmFair, a British animation studio, and it was narrated by Sterling Holloway, it sounds like. Anyone know if this commercial been preserved anywhere? I've never seen it mentioned before, not even on 'the duck-wikis'.