Men’s “plus-four” pants were popular with which sport?
Since the 19th century, men had traditionally worn knickerbockers, baggy pants cinched above the knee. But after World War I, a new style was introduced: trousers that were 4 inches longer (hence the name) and cinched below the knee. The freedom of movement given by plus-fours made them popular with golfers, but they were soon adopted for everyday wear by fashion icons such as Edward, Prince of Wales.
Source: Glenmuirs