Ivy-style tweed sports jackets and suits are often distinguished by detailed quarter-inch stitching from the edge of the lapels down the front of the jacket. This distinctive feature is usually echoed by lapped seams that run across the shoulder, down the back seam, and around the pocket flaps.

But how did it get there?

Everyone who’s considered this question agrees that the stitching gives the jacket a sporty look, and that the addition of what English tailors sometimes refer to as a “swelled” edge makes for a casual, jaunty touch. It’s certainly something that one would never expect to see on a fine worsted or flannel business suit. We seem to intuitively recognize that this almost imperceptible detail is at home more in the country than in town, that this rakish element produces a casual, country effect.

And, as it happens, our intuitions are once again right. The quarter-inch stitch is in fact a vestigial visible trace of something long gone from utilitarian practice — and memory. It hangs on as decor rather than as a functioning detail, but like the two buttons in the small of the back of a tailcoat (originally used to button the tails when in the saddle), the quarter-inch stitch once had an important function. At least if you lived in the country and followed country pursuits.

Tweed jackets and coats, it should be remembered, were the Victorian equivalent of sportswear, the most useful country garment a gentleman could devise at the time to protect himself from the cold and wet of a day’s hunting, stalking or riding. The wool fabric is hearty and handsome, absorbent, abrasion-resistant, and warm. But without the tailor’s art, it would become a baggy mess after a few short hours on the moors. That’s where the quarter-inch stitch comes in.

In order to prevent the lapels (and therefore front of the jacket) from collapsing when soaked with rain, some unacknowledged tailors figured out that a reinforcing row of stitching down the front edge of the coat would keep the whole thing better in place. And it does. The additional stitching along the lapel helps the coat keep its shape by holding the cloth – both the inside and outside layers — together when wet.

Today we really don’t wear our sports jackets in the rain: various synthetic fibers and waxed fabrics have replaced wool for so many occasions. But that handsome quarter-inch of stitching is there as a jaunty reminder that these handsome coats we now wear as mere plumage were originally designed with great utility in mind. — G. BRUCE BOYER

boyer-bioLegendary menswear writer G. Bruce Boyer was men’s fashion editor at Town & Country throughout the ’70s and ’80s. He has recently returned to writing for the magazine.

Above image is a 1962 illustration from Brooks Brothers, which features swelled edges on its current Own Make sportcoats.