We found a reference to this spanking in the comic strip Seein' Stars, and decided to research the film it referenced. What we found was that it had been discussed at The House of Richard Windsor, and CSR readers are encouraged to follow the link to that page, although we will repeat the essentials here after providing some preliminary background information.
First, there were two films we need to know about, Dear Ruth in 1947 and its second sequel Dear Brat in 1951 (the first sequel, Dear Wife in 1949, need not concern us here). Dear Ruth had been based on the play by Norman Krasna, a fact we will refer to later. Let's take a look at three publicity stills from Dear Ruth since that is the film referenced in Seein' Stars.
Publicity still #1 from Dear Ruth with Edward Arnold and Mona Freeman (click to increase in size).
Publicity still #2 from Dear Ruth with Edward Arnold and Mona Freeman (click to increase in size).
Publicity still #3 - the spanking at last! - from Dear Ruth with Edward Arnold and Mona Freeman.
But was there an actual spanking in Dear Ruth? Here is what our own JimC had to say about it:
"From what I remember of the movie (DEAR RUTH) Mona had been telling her father about how she had written the letters and some other items and her father was going to exercise some paternal discipline that she needed. I also heard that this scene was somehow cut out of the movie before release and while the pictures exist in some uncut release hence the 3 that are the same outfits it is not available of most copies of it. I do think I heard about as one of those publicity stills that was not in the movie like FULLER BRUSH MAN or JANIE GETS MARRIED. Great pics of a spanking that never happened."JS666, familiar to CSR readers for his many contributions here and elsewhere in the spanko world, actually remembered the Seein' Stars Sunday comic strip:
"The way I heard it, from a Ripley-style column on Hollywood gossip in the Sunday comics section of the papers, they actually filmed the spanking for “Dear Ruth,” but it didn’t make the film. The interest hook was that Arnold, who was right-handed, had broken that hand and had to spank with his left, accounting for the wrong-hand pose we see here. (Why they couldn’t just turn the girl around was not explained.)"And finally Harry (a/k/a Solicitus) did some further research:
"I’ve now read Norman Krasna’s script for Dear Ruth. Miriam is threatened with a spanking in the first act and near the end of the play she admits that she deserves to be punished, and indeed says she is devising an additional punishment for herself over and above whatever her father does to her. And then – nothing! So the school in 1954 must have decided there was something missing and added the spanking."We're certainly with the school (Harry is referring to a school that mounted a production of the original play) - the play as written presented a colossal missed opportunity when it should have had a very nice spanking scene, so why not add one?
Another opportunity arose with the sequel Dear Brat - the title alone almost
promises a spanking. And once again, we have some very nice production stills
(below). And yet it appears there was no spanking in the movie - rats! 
(We've checked
Chross's Movie Data Base and searched our own
Bulletin Board as well. There is a mention under the topic Publicity Stills but not any more information than we have already covered.)
On the plus side, all three spanking photos are good, and the last two are excellent! (Apparently some Hollywood genius realized you could solve the problem of Edward Arnold's injured right hand - was it still injured in 1951? - by simply turning Mona Freeman around, as JS666 suggested above). And what a lovely spankee she makes!
Publicity still #1 from Dear Brat with Edward Arnold and Mona Freeman.
Excellent OTK positioning, Mona appears genuinely distressed (sorry, Brat, but spankings
have to hurt if they're going to do you any good), and there are witnesses enjoying the
spectacle to add to her humiliation!
(Click to increase in size).
Publicity still #2 from Dear Brat with Edward Arnold and Mona Freeman. This time Mona wears an expression of sly delight at getting the spanking she has well earned (click to increase in size). Posted by the Web-Ed on 12/13/2019.
The complete poster, which we somehow forgot to post last time, courtesy of Richard Windor. Posted by the Web-Ed on 03/20/2020.
