William Herald attended school in Sydney and during this time won his first junior championships. In addition to the silver medal in the freestyle relay at Antwerpen, he gained a certain reputation for his protest against the first final in the 100 metre freestyle when he was hindered by American Norman Ross. In 1922, Herald was Australian champion in the 100 yard freestyle and was also nominated for the Games in Paris, but the bank where he worked would not grant him a leave of absence. After the 1920 Olympics, Herald also played rugby for Manly Life Saving Club and played Aussie Rules football. In 1940, he enlisted for World War II and served with the Australian Headquarters Guard Battalion until 1945, but later returned to his bank job. After being posted by his bank to various locations, he returned to Sydney after retiring.
Australian military records give his year of birth as 1902, but he lied about his age in order to enlist during World War II.