In 1945 bums were there to be whacked.

I thought that line had a different meaning - did it hurt in other ways than just the sting in the bum?
because clearly it hurt the mother as well, and I wonder whether that diffused its way through to the boy.

That might have been "Curse of the Cat People".

With such a title as that I've got to watch that one

that must have left the audience cat-atonic with fright

in "Meet Me in St. Louis (1944)," starring Judy Garland, Leon Ames (the father) tells Margaret O'Brien (the little sister of Judy Garland's character) "remind me to spank you at bedtime."

Here's a spoiler filled description from spanking art"
After the death of his wife Irena (Simone Simon), Oliver Reed (Kent Smith) has married former co-worker Alice Moore (Jane Randolph) and they now have a six-year-old introverted daughter Amy (Ann Carter). Amy has trouble at school because she spends too much time daydreaming, and Oliver tries to encourage her to make friends. After Amy finds a photo of deceased cat-woman Irena, whose name is never mentioned in the house. Irena's ghost appears to her and the two strike up a friendship. At the same time, Amy befriends Julia Farren, an aging actress who is alienated from her own daughter Barbara (Elizabeth Russell, who also appeared as a sinister cat woman in the previous movie - perhaps the same character).

Reed and his family have left New York City, and now live in Tarrytown, New York. The legend of the Headless Horseman plays into the sense of foreboding in the plot.
The spanking scene

Oliver takes Amy to their house's doorstep and tells her to look all around the garden very carefully and then let him know if her "friend" (the ghost of Irena) was there. Amy sees Irena stand under a tree and tells him she's there. Oliver, who can't see the ghost, tells her there's nothing there but Amy insists that she's saying the truth. Oliver tells her that if she keeps insisting that this woman she calls her friend is in the garden, he has to punish her. "You understand?" — "Yes." — "Alright. Now - tell me what you see." — "I see Irena."

Without further words he takes her back inside the house and leads her upstairs. There is no violence on his part and no resistance on her part. Her mother Alice watches them worried. "Amy's never been punished before. Not that way." — "It's best not to interfere." — "I suppose so. I'm sorry I made such a fool of myself." — "After all, for a spanking - it's an important occasion." — "I'll be alright in a minute."

The actual spanking is neither shown nor heard, but the anticipation is good. Oliver is shown walking down the stairs, and Amy is shown crying in her room, until she is comforted by Irena.

The actress Ann Carter also appears as a teenager in a spanking-related context in the 1949 movie Blondie Hits the Jackpot.

Well, possibly to the boy eventually, due to his mother's obvious hesitation to strap him and her facial expression of reluctance, but his little sister didn't observe any of that, so I'm presuming her reference at that time was to the spanking's physical effect on her brother.

What she might have meant was "Did it hurt as much as being punished by Daddy used to?", since before his abrupt death their father had apparently been the family disciplinarian...

--C.K.

I think you are right insofar as the characters in the film are concerned, I was thinking of the thought which was supposed to be generated in the audience's minds. After all, stories are only the vehicle for saying something, often not what the story is about on the surface. Famously Jaws isn't about a shark.

Alice's friend's comment is actually: "After all, a first spanking - it's a very important occasion" - which is a better line, and makes more sense. (I used it as the epigraph to my story 'Birthday Girl'.)

That's what I get for copying and pasting... I've seen the seen and knew the line, but just copy and pasted.

Ah, for the good old days of violence epitomised by that famous British newspaper heading from 1944, "British push bottles up Nazi rear".