I read all of Rutt. Then, I looked at a bunch of his original sources, and read him again. Then, I went to the shop and made needles and experimented. Then, I went back and re-read passages.
Note for example that I compare what he says on page 20 with what he cites from Howitt on page 120. On page 122, Rutt discards Howitt's eyewitness description without a stated reason. Rutt's eyewitness (Sedgwick, pg 122) has abandoned the curved needles by the time Rutt meets her. Why? I propose that she stopped swaving because swaving is a high effort activity. It is hard work. It was a way for a commercial knitter to knit as much as possible per hour, and Sedgwick was no longer getting paid by the piece, so she did not put in the effort into knit extra fast. The swaving needles were thus surplus, and got lost – maybe a metal drive during WWll.
Rutt assumes that the needles were bent of long usage, but does not state a basis for that assumption. However, a look at old museum needles shows two classes of bent needles. Needles randomly bent from long usage show clear differences, and needles with a deliberate bend in them. The Dentdale knitters put a deliberate and specific bend in their needles. My first swaving needles looked like the bent from age needles. Once I understood swaving, I went back and re-bent my needles. Re-bending the needles was a real effort, but then, my needles looked the deliberately bent group of needles in the museums. Those needles did not get bent by usage. Rutt should have figured this out.
Rutt does not consider the possibility that there might be a very fast, commercially oriented hand knitting technique that required a knitting sheath and needles with very specific curves. He does not think about the physics or the ergonomics of swaving. Old Mrs. Sedgwick no longer had a need to knit very fast, she no longer had the strength, she no longer had the skills, and she no longer had the old curved needles. She no longer had the big knitting sheath. She was not a good witness for the technique. Yes, she did show him one or two of the 3 or 4 knitting techniques that they used, she just did not show him all all of them.