His Holdom ancestors had lived in the Spitalfields neighbourhood of London for nearly three hundred years, after fleeing France during the St. Bartholomew's Day massacre.
Holdom immigrated to the United States at the age of seventeen, settling in Chicago in July 1868.
He was a successful lawyer, particularly in cases involving wills and title to real estate.
In November 1898, Holdom was elected as a judge of the Superior Court of Cook County.
He was also involved in Trinity Episcopal Church, the Republican Party, and the Union League Club of Chicago.