Flannel Suit & Fedora at The Paris Flea Market

Vintage gray flannel suit

Rear of grey flannel suit t evolved from a style of coat known as the "Norfolk jacket", whose belt extended all the way around to the front. Around World War I(?), military jackets began to appear with half belts in the back. As WWI ended, manufacturers of civilian clothing began to offer sporty suits with belted-back jackets. 

Here in the U.S.A., the style was popular throughout the 1920s and most of the '30s. By 1940, however, the belted back was disappearing from suits and sportcoats. It lasted for a while longer on gabardine "Hollywood" ("Ricky") jackets, then pretty much disappeared until the early '70s, when it popped up again on polyester sportcoats and suits. (Remember those nasty polyester "Angel's Flight" suits made by Levi Strauss?)

The belted-back jacket or suit was considered sporty attire. It could be worn to work by certain professionals (such as reporters and theatrical agents) and not by others (such as bankers and lawyers).