A double breasted 6 to 8 button vest matched the suit with one or two slit pockets for a pocket watch on either side. Even if the man wore a wrist watch, having a vest without a pocket watch pocket was shoddy.
1920s mens summer suit in grey stripe. Double Breasted, wide leg. More at VintageDancer.com
Late 20s traditional men’s double breasted suit in grey stripe
The suit trend for the British (and British ruled countries) was a conservative double breasted jacket, with wide notch lapels, wide natural shaped unpadded shoulders, narrow sleeves, a high waist nipped in tight to the rib and then curved gently around the hip. The curvy silhouette was oddly feminine at a time when women’s wear was flat and masculine.
In the early years suits often had half belts along the back a carry over from the military look in the teen years. With men returning from war in better physical fitness than ever the suit was shaped to accentuate the lean and muscular physique. A shorter jacket accentuated a built torso and long legs. The very slim “jazz suit” disappeared after 1923. The natural body shape was the preferred fashion.