Following WWI (1914-1918) the morning coat and the lounge suit became popular; only the old and conservative stayed with formal frock coats. As the 1920s progressed it became the norm to wear the morning coat during the day for formal occasions only, with a lounge suit regarded as acceptable casual wear and formal white-tie-and-tails for the evening.
In America, the long fuller dress of tails was replaced by the shorter dinner jacket for the evening and the ‘black tie’ became the standard neckwear in both Britain and the States. The white tie was not displaced entirely for evening wear, though.
Men’s suits in the late 1902s become looser and baggier; men were wearing wide, straight leg trousers with prominent turn-ups, the so-called ‘Oxford bags’. The trousers measured as much as 23 inches at the cuff. The trousers had a high waist and this became the norm until the 1940s and beyond.
The younger generation took to wearing single-breasted suits, while the older men preferred the double-breasted ones. In the 1920s, double-breasted waistcoats with two columns of four buttons on each side became fashionable.