I'm getting a bit rusty on some of the pattern numbers but I'm sure you are right, Glen. We called it "crimped", not "ruffled"!
I'm not sure of the age of Tony's example but yours, Anne, is right in the middle of "my" period. The T centre handle and extension were by Wm Lindop of the Birmingham area. I have fond memories of him as he kindly re-plated the hub caps of my Standard Vanguard! At that time the underside was certainly "sand" (i.e. less toxic abrasive) blasted before the star was polished off. Pre-WW2 they might have been acid etched, but I'm not sure about that. Acid work wasn't re-started after the war, at least when I was there.