Jono, in 22a the full thematic (two words 4, 6) is well-known outdoor (cold weather) gear, but often referred to by a different related term. I own a pair. See for instance https://tinyurl.com/muka2axn
In the light of what jono said @11 about 6d, I now wonder whether, as I originally thought, Brockwell intended it to be thematic or thematic-adjacent.
Any thoughts?