Porter, Classon Emmett (1814–85), non-subscribing presbyterian minister and writer of local history and biography, particularly that of Irish presbyterianism, was born in Artikelly, near Limavady (then called Newtonlimavady), Co. Londonderry, first child of William Porter (qv) (1774–1843) of Artikelly, leading presbyterian minister who became the first moderator of the remonstrant synod (1830), by his second wife Eliza Porter (née Classon) (d. 1852, Drumahoe); he had elder half-siblings by his father's first marriage. His mother, of a Dublin presbyterian family, was a governess and later headmistress of a girls’ school in Derry city until her marriage. Porter was educated at the Academical Institution, Belfast (now the RBAI), and in England at Manchester New College, York (1828–34). At the early age of 20, he became minister of the non-subscribing church in Larne, Co. Antrim, part of his installation being conducted by his half-brother Revd John Scott Porter (qv) (1801–80), at that time minister of Rosemary Street non-subscribing church, Belfast. Larne was to be Porter's only congregation, as he remained there until his rather early retirement in 1875. His history of the church, ‘Congregational memoirs, no. 2: Larne and Kilwaughter congregation’, published originally in fifteen parts in the Unitarian Christian (Sept. 1863–Dec. 1864), was reprinted with a portrait photograph (the original of which is in his old Larne church) in book form (c.1929, 1974). His first set of ‘Memoirs’ had treated the nearby Ballycarry congregation (Unitarian Christian, Feb.–Aug. 1863).
An advocate of the national school system's principle of interdenominational secular education, Porter became a visitor and manager of some local national schools and later a district inspector. In 1839 he established the first classical (secondary-level) school in Larne. A year later he set up his Female Industrial School in the church grounds, where girls from low-income backgrounds, besides receiving conventional lessons, learned fine knitting and sewing, and sold their handiwork. He was instrumental in promoting adult education in Larne, opening a congregational library in 1836 and using the schoolroom for diverse meetings and lectures. From the 1840s he held the leases of two farms; after residing and farming at Drumahoe for about twenty years, he moved into Main Street, Larne in 1862. He developed business interests in the town, becoming in the early 1860s a founder-member of Larne Markets Ltd.
Porter played an active role in church controversies through such writings as Dissenters’ chapels bill: arguments in defence of the recent attacks on the congregational property of unitarians considered (1844), and Irish regium donum and ministerial maintenance (1884). He was a frequent contributor to the Bible Christian and the Disciple. His publications on personages in the church included Irish presbyterian biographical sketches (1883) (reprinted from the Northern Whig, in which many of his writings first appeared) and Seven Bruces: presbyterian ministers in Ireland for six successive generations (1885). A detailed biography of his father in fourteen manuscript notebooks was latterly in the possession of the Rowan family, Malone Rd, Belfast, as was a genealogy of the Porter family compiled in 1909 from his research. His extensive notes on the Antrim Macdonnells are in PRONI. His biographies of non-presbyterian subjects include A short biography of Frederick Augustus Hervey 4th earl of Bristol and bishop of Derry (1884) and Ulster biographical sketches (1885). In the early 1870s he produced, almost on a weekly basis, articles on Larne's local history, including that of the churches of various denominations and traditions.
Porter married (1853) a distant relative, Eliza Ann Wallace of Omagh, Co. Tyrone, a granddaughter of his father's stepsister; they had three sons, the youngest of whom, also Classon Porter, became a barrister in Dublin. A brother of the elder Classon Porter, James Nixon Porter, also was a minister; another brother, Francis, went to Africa to join their stepbrother William Porter (qv) (1805–80), who became attorney general of the Cape. The money bequeathed by William to Classon Porter may have assisted him in restoring Ballygally castle, near Larne, his residence for the last ten years of his life. A large Celtic revival cross marks his grave in the Church of Ireland burying ground at Cairncastle, Larne.