oddly I was reading this story yesterday because someone linked to an item of clothes from a shop which also contained a silk code scarf: https://adversarialfashion.com/products/wwii-code-cipher-sca...

it's unclear from the images in the shop but the code isn't the circuit diagram-ish things but a table in the middle, which reproduces this, an actual SOE silk code: http://www.jproc.ca/crypto/silkcode_chart_b.jpg

This is apparently a 'Worked Out Key' cipher, not a OTP as mentioned in the article, but both were in use due to Leo Marks https://en.wikipedia.org/wiki/Leo_Marks#:~:text=Developments....

(in fact, here's a photo of Leo with one of these code tables https://www.historynet.com/was-this-the-uks-worst-spy-failur... )