Our mystery lady was indeed, as the estimable Bill guessed, that heavenly creature born Shirley Schrift, but known and loved the world over as Shelley Winters.
It's actually one of a number of candids taken during the filming of one of her early masterpieces, South Sea Sinner (aka East of Java), in which she shared the screen with, of all opposite numbers, Liberace.
Altogether, the series of photos, of the star in strappy sandals and smock on her lunch break, amounts to something of a comprehensive tour of the Universal lot, whose standing sets of saloon and jungle gave the picture what atmosphere it had. Here we have the alarming vision of an infinite number of Shelleys in a set of dressing room mirrors.
And here Shelley proves the skeptics wrong: she was literate.
One thing puzzles me about Bill's guess, though. This, he thinks, is a look that's "too trashy" for Betty Hutton. Huh? Nothing was too trashy for that blonde...