Oh! I actually know a very tiny bit about this.

First, the waist-bags you are describing were actually called pockets. Modern literature generally specifies them as "tie-on" pockets, but at the time there was no differentiation. Also, women's pockets shifted from the "tie-on" pockets to sewn-in pockets probably somewhere between 1840 and 1870, but the tie-on pockets were still sometimes used. Since MN takes place in 1899, Polly could theoretically have had either.

I knew some of that already, but a dress historian recently did a video on the evolution of pockets where she covers this.

It is also entirely conceivable that Lewis just didn't know about the pocket discourse (complaints about the limitations of pockets are not a new thing!).

Posted by: @dot

 

It is also entirely conceivable that Lewis just didn't know about the pocket discourse (complaints about the limitations of pockets are not a new thing!).

Can confirm, I didn't realize until very recently what barbarically small pockets women/girls have to put up with. 

Barbaric is a good word for it, @Glenwit.

That was a very informative and amusing video, @Dot.  Right now all I can think about is that C.S. Lewis was so ahead of his time that he somehow sensed the "It has pockets!!" memes of the future.

The rings-in-the-pockets element is such a central component to Polly and Digory's adventures and I really hope the costuming department for the upcoming film/series doesn't cop-out and have Polly wear a pair of trousers. You can go on interplanetary adventures in dresses, too.

Posted by: @rose

That was a very informative and amusing video, @Dot.  Right now all I can think about is that C.S. Lewis was so ahead of his time that he somehow sensed the "It has pockets!!" memes of the future.

And all I can think of now is Gollum asking about "pocketses."  

Honestly, I always kind of assumed that Polly would have worn a typical frilly Victorian dress (the Bayne's illustrations portray it very well) and that somewhere in the lining thereof, there would have been a small pocket for. . . something.

Definintely an interesting, albeit unexpected thing to find in here being discussed.

I always assumed she wore a smock or pinafore over her clothes which had pockets. If she was playing outside, or helping her mother with the housework, she would have worn one.

@cobalt-jade This is the most likely correct answer. Baynes' pictures put Polly in a 'sailor suit' dress, with no pinafore. I suspect that if she was playing up in the attic, getting her pinny dirty would be less trouble than her dress.

I was also re-reading the Magician's Nephew and while I was reading I have a guess that Polly's dress has only one pocket on the left hand side. 

If I tried to stretch across and get my right
hand into my left pocket I mightn't be able to reach it, - Magician's Nephew 

Polly didn't just put her hand in her right pocket with her right hand because that would've been easier, but instead she tried to reach her right hand into her left pocket concluding her dress had one pocket. 

Posted by: @kingedthejust

I was also re-reading the Magician's Nephew and while I was reading I have a guess that Polly's dress has only one pocket on the left hand side. 

If I tried to stretch across and get my right
hand into my left pocket I mightn't be able to reach it, - Magician's Nephew 

Polly didn't just put her hand in her right pocket with her right hand because that would've been easier, but instead she tried to reach her right hand into her left pocket concluding her dress had one pocket. 

There's a bit earlier in the book that explains this. Polly and Digory intentionally put the yellow rings in their left pockets and the green ones in their right. Jadis is holding her left hand, so she would have to reach with her right to get the yellow ring. So, Polly has pockets on both sides.

However, this made me look up the bit when she gets the toffee out of her pocket for dinner:

"I say," said Polly, "I've still got the remains of that bag of toffee in my jacket. It'll be better than nothing."

"A lot better," said Digory, "but be careful to get your hand into your pocket without touching your ring."

So, Polly put the rings in her jacket pockets rather than skirt, pinafore, or a tie-on.

Her jacket?!

Just goes to show how much influence the illustrations have on our idea of them.

Edit:

What edition is yours? 

I've just checked my 1973 edition, and it says,"..in my pocket."  (Not jacket)

@ KingEdTheJust: I was also re-reading the Magician's Nephew and while I was reading I have a guess that Polly's dress has only one pocket on the left hand side.

If my memory serves me, I always had a pocket on the right hand side. Especially as in those days we were encouraged to be right-handed. It was worse at the beginning of the century. Boys always had lots of pockets, to hide in them everything from skinks to marbles. But girls weren't supposed to do such things. 

For some reason, as I'm reading this discussion, I keep getting the Polly Pocket jingle (from the TV ads of the '80s and 90s) stuck in my head...  

That aside, it's a very interesting topic and something I know I didn't even stop to think about when I first read the Narnia books, as most of my clothes had pockets and I never stopped to think there was a time when girls and women didn't have that luxury!

The Magician's Nephew is set in 1900, when Lewis himself was a toddler (he was born in 1898). So he's writing about an era that he himself knew, if only through a very young child's eyes. I'm guessing, though, that as a small boy he possibly never stopped to notice whether or not girls had pockets in their dresses or aprons, and writing MN some 55 years later, he might not even have thought about that factor, but just assumed they did!

I'm going with @cobalt-jade's suggestion that Polly wore a pinafore or smock with pockets in it, which would definitely help to keep her dress clean if she was playing outside or in the attic, both of which she does during the story. That seems pretty natural for the time period while allowing the plot to work!

Posted by: @dot

So, Polly put the rings in her jacket pockets rather than skirt, pinafore, or a tie-on.

Ah, now that's interesting... my 1973 Puffin edition says "pocket" there, but my 1998 Collins edition says "jacket". I'm guessing the latter must be a misprint that got in somehow. I really can't picture a late Victorian / borderline Edwardian era girl wearing a "jacket" of any description! Unless she was several decades ahead of her time, fashion-wise...  

Posted by: @coracle

I've just checked my 1973 edition, and it says,"..in my pocket."  (Not jacket)

Posted by: @courtenay

Ah, now that's interesting... my 1973 Puffin edition says "pocket" there, but my 1998 Collins edition says "jacket".

Intriguing. I went and looked it up in all of my copies: 1970 Collier says "pocket", 2000 Harper Trophy Edition says "jacket", 1994 Harper says "jacket", and 2004 Harper omnibus says "jacket". Does anyone have a copy of a first edition?

Posted by: @courtenay

I really can't picture a late Victorian / borderline Edwardian era girl wearing a "jacket" of any description!

I actually spent several minutes looking up fashion plates and pictures of late 1890s and early 1900s children's clothing last night because I kept thinking about what Polly's jacket might have looked like. They did wear jackets, but most of the images I've seen show jackets in more formal wear rather than informal play clothes that Polly was probably wearing. Also, Polly actually had the opportunity to change clothes because she went home after they brought Jadis to London. And apparently she was sent to bed because she rejoins Digory "the moment she was allowed out of bed."