William G. Irwin was a capitalist and successful sugar planter in the Kingdom of Hawai'i. He was born in England, and emigrated to Hawaii with his family while still a child. He would remain a British citizen throughout his life. Educated at Punahou School, he was in the right place at the right time to make a lot of money in the sugar plantation market. After the passage of the Reciprocity Treaty of 1875, Irwin formed the William G. Irwin & Co partnership. California entrepreneur Claus Spreckels offered him a separate partnership in 1881, a union that would come to include the Spreckels interests in sugar plantations, and have subsidiaries in banking activities and ship building. Two decades later, after amassing a fortune in his association with Spreckels, Irwin moved away from the plantation activities and relocated to San Francisco, where he continued his affiliations with financial institutions. At his death, Irwin's estate was estimated to be in excess of $10,000,000. His only child Helene married the first time into the wealthy Crocker family of California, and through her second marriage to Paul I. Fagan, became an owner of the San Francisco Seals baseball team.

John Smith Walker was Minister of Finance of the Hawaiian Kingdom, and interim Attorney General of the Kingdom of Hawaii, under King Kalākaua.