Hi! I sure do remember the 101801! That was a fun thread as we were splitting hairs on coat fit!
I completely agree with you on shoe fit, and your Harrod's SA on shoes stretching out is spot on.
A "C" is for the width of the shoe (B is standard), and often, the difference is in the toebox and wide part of the foot, where the bunion is! I think you will like the C width for more comfort. C is rare, almost non-existent, in the US for a closed toe shoe such as a pump.
C is standard though for thong sandals as feet tend to "spread" when walking with thong sandals. I think nearly all my thong sandals are C width which I appreciate.
Since we are talking about widths and sizes...
I thought it might be fun and interesting to share how to read a shoe box in case you or others might be interested.
I got started on this because I have to order all my shoes as none of the dept stores near me carry Chanel shoes.
I am also super picky about heel height, and my max heel height is 85mm, not 90mm.
A few times, the SA would say "3 inches" but the height actually turned out to be 90mm (3.5"). It's doesn't seem like a lot of difference, but 90mm heels kill my feet and squishes my toes, so I can't deal with them. That's when I started asking my SA to verify the actual heel height from the box before he sent them to me.
That was a few years ago when I still wore high heels to work! Now, the slingback height of 65mm is my max height!

Below is the shoe box to my denim Chanel ballets.
To the left, above the photo of the shoe is "38" for my size, size 38.
To the right is "23P" for 2023, Spring (P=Printemps, which is Spring in French)
Underneath is the style code "G02819..."
Then, do you see the little "10B?" That stands for heel height and shoe width.
The "10" is the heel height in mm. In the case of ballets, it is a 10mm heel.
The "B" is the width, as in B width.
Slingbacks have a 65mm heel, so the number on your box would be 65C, for 65mm heel height, C width.
The second photo is my shoe box to my beige slingbacks. Wow... I just realized I got them so long ago!
It says REV instead of the year/season (e.g. 23P) because the beige/black cap toe are classic, revolving stock.
You can also see the “65B” on my box for 65mm heel height and B width.
Hope that was interesting and fun!
On your gorgeous slingbacks.. yes, take them out!
For your test run... go to Harrods! Take Uber (or Gett) to Harrods, walk around and shop, then have lunch at one of their restaurants (or coffee/tea at The Coffee Bar) and people watch! It will be so much fun.
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