A reader wrote recently asking my opinion on patch and flap pockets and I responded that they weren't my favorite but they have been, for some unknown reason, a traditional styling element on gabardine suits in the United States. Here Apparel Arts shows them on tan gabardine in both city and university settings. The only difference is the top stitching on the pockets on the campus suit.
I remember, in the distant past when Brooks Brothers was my authority on all matters related to dress, that patch and flap pockets were the default on bespoke tweed and gabardine suits unless I requested something else specifically. I know I had them, top stitching and all, on a tan gabardine as well as a gray herringbone that I finally donated to charity last year.
The downside of patch pockets in general is that they are a bit smaller than standard pockets, and more inclined to bulge. That's not a good thing for a man who, like me, uses every pocket that he has. On the positive side, they don't have undersides that need to be hidden by lining inside the jacket, although that's usually something that matters only to summer suits and neither tweed nor gabardine is a suiting I reach for on a hot day.
That said, I have one tweed with patch and flap side pockets that I ordered just to remind me of the days when I spent my Saturdays at BroBroClo, the name my now long retired salesman had me write on the many checks I left there.