Now, when I thought "older" meaning, I was thinking for some reason that "older" more than a hundred years. But I just came across Rudyard Kipling's Just So Stories again (1902), and I couldn't help but notice that the single solitary shipwrecked Mariner in "How the Whale Got His Throat" has "nothing to wear except a pair of blue canvas breeches, a pair of suspenders (you must particularly remember the suspenders, Best Beloved)". I think it's reasonable to assume that the suspenders are there to hold the breeches up, not some missing stockings. It's also probably reasonable to assume that since this isn't Captains Courageous, Kipling wasn't trying to use American terms (particularly considering the Mariner is "Hibernian" and rhymes "eat" with "grate").
So . . . does anyone have a more precise idea of when the meaning of "suspenders" changed in BrE?
(Incidentally, why do the Brits keep changing the meaning of words describing outer garments to describe underwear instead? /facetious Although, suspenders . . . vests . . . knickers (see: knickerbockers)?)