Thanks for all your comments on my SOS post! This is my second attempt, in pink and white silk (1200 dernier) from Devere Yarns. This silk gives a very smooth, soft and shiny braid :-). The braid is about 1 cm in width. In the upper row, you can clearly see the point where I reversed the directions of the tablets. It's not so obvious as in my first attempt, but I'm not sure whether I like it: it really disrupts the smooth surface... I also found it difficult to maintain the tension of the weft. I guess that in my next attempt, I have to pull the weft a little tighter, because now it really shows at the edges.
(A reenactors dilemma: reversing the tablets is done in the original work, but the braid looks much better without it. To go for "authentic" or to go for "beautiful"? I'm inclined to go for beautiful...)
I want to use this type of braid to make some 14th century garters. (I've put my embroidery projects on hold and I'm currently focusing on a set of ca. 1370 clothes. )
You can find a picture of the original in
Crowfoot, E., Pritchard, F., & Staniland, K., Textiles and Clothing c. 1150-c. 1450. Medieval Finds from Excavations in London, 4. London: The Boydell Press, p 133 braid C.
A pattern of this braid can be found here.