Horden was born in Exeter, England, the eldest son of William Horden (a printer) and Sarah Seward, and received his early schooling at St. John's School, paid for by charitable donations [REF].
Horden was an active member of his local Church of England congregation (Church of St. Thomas the Apostle, Exeter) and regularly attended the vicar's Bible class, which offered information on the mission opportunities available in addition to a Biblical education.