For the past few centuries, men had worn some variation on three-piece suits. Edwardian upper-class men in particular had been very formal, changing clothes several times a day as propriety dictated.
The war changed attitudes and did much to level the classes, which reflected in fashion. Younger men, in a switch from wearing the clothes of their elders, adopted a look all their own with baggy plus fours and wide-legged trousers. Suits were simpler, with just slim, unpadded jackets over the trousers, and fabrics and colors were lighter and brighter than anyone had seen in years, reflecting the brightness of the music, theatre and good times.
1920s Men’s Fashion