I failed. The best collection I found (linked above) consists of 400-pixel scans of just six of the eight plates from the book. There are quite a few dubious ebook editions available, but they're all DRMed or paywalled, with no indication that they are careful electronic editions respectful of the artwork. Since the book itself is so easy to find, I thought it was a good time to deploy some of the shekels so generously donated by our Patrons. I've ordered a beat-up edition that won't be a loss to bibliographic history if I have to take it apart in order to get a proper scan. From the bookseller's description:
Eight plates. Originally published by Swan in 1941; this is the fourth edition. Standard fare for the rubber shop trade in London in the 1950's and early 60's, as this cataloguer can well attest. A useful compendium on corporal punishment and its various instruments. Leatherette, front hinge starting, missing front free endpaper. Printed on standard 'War Economy' paper. Fair.
My intention is to scan the artwork at ridiculously high resolution, and then to make a decently hi-res scanset available to the public, with a higher-res set available to Patrons only (at least for a time).