https://www.britishmuseum.org/collection/object/E_Oc1980-Q-1037">https://www.britishmuseum.org/collection/object/E_Oc1980-Q-1037
Never seen a pouch constructed in this manner, looks like a series of flat-braids interwoven at the sides. The material and length is interesting also. Looks very durable and functional.

I think Morphy has done some of this wider style braiding. That sling does indeed look really nice.

The main part of the pouch is likely made with "flat twill oblique interlacing with longitudinal ridges" (Speiser, Manual of Braiding)
With binding (over 2, under 2) and (over 3, under 3) mixed, as far as I can see. But it is hard to tell for certain. See the pictures appended for the over 3, under 3.

On the borders, there is some magic happening, which I can't figure out on the fly. Likely one strand is split up into multiples and vice versa. A picture of the back side would be nice.
A very nice piece.

Looks like we need a British slinger to head on over and take  the sling back so we can get more pics!

The key know how in this sling is in how the splitting up of the strands is made at the transition of pouch to retention and release cord. As well as the edges. If someone makes a tutorial for that, I will certainly read it 

I'd like to figure that one out as well. It is on my bucket list, but I'm quite busy at the moment.
However, I can share my my notes.

To-Do:
- print out the pictures and count the strings in each "row".
- then make a "pattern chart" / sketch.
- find the points where the strings split up.

Notes:
- the pouch starts likely with a 5 strand flat plait.
- loose fibers might be better suited.
- Get some inspiration from panama hat braiding videos on how to handle all the strands at the same time.

I think I'm getting closer.

I started with 10 strands for simplicity.

Section 1 (on right): 5 strand fishtail (grouping 2 strands).
Section 2: 1 cord, over 2, under 2 (repeat other side)
Section 3: 1 cord, over 1, under 2, over 2 (repeat other side)
Section 4: 1 cord, over 2, under 2 (repeat other side).

It seems to take an addition of 4 cords total to get an additional "herringbone" column if one keeps with the "over 2, under 2" pattern. Section 3  only has 3 herringbone columns because I just used 1 cord on the edge instead of 2.